diff --git a/.vscode/settings.json b/.vscode/settings.json
index 6e42470..f608572 100644
--- a/.vscode/settings.json
+++ b/.vscode/settings.json
@@ -55,5 +55,8 @@
   "C_Cpp_Runner.useLeakSanitizer": false,
   "C_Cpp_Runner.showCompilationTime": false,
   "C_Cpp_Runner.useLinkTimeOptimization": false,
-  "C_Cpp_Runner.msvcSecureNoWarnings": false
+  "C_Cpp_Runner.msvcSecureNoWarnings": false,
+  "clang-tidy.compilerArgs": [
+    "-std=c++17"
+  ]
 }
\ No newline at end of file
diff --git a/L3B b/L3B
new file mode 100755
index 0000000..3e1d990
Binary files /dev/null and b/L3B differ
diff --git a/Makefile b/Makefile
index 68509bc..2b7045c 100644
--- a/Makefile
+++ b/Makefile
@@ -1,5 +1,5 @@
-TARGET = CHANGEME
-SRC_FILES = main.cpp
+TARGET = L3B
+SRC_FILES = main.cpp string_functions.cpp test_suite.cpp
 
 # Tyler's custom makefile extensions for CSCI200 (anyone can use these if they want)
 .DEFAULT_GOAL := all # Necessary so `make` doesn't run the "pack" target, as it is declared before "all"
@@ -80,4 +80,6 @@ depend:
 .PHONY: all clean depend
 
 # DEPENDENCIES
-main.o: main.cpp
+main.o: main.cpp test_suite.h
+string_functions.o: string_functions.cpp string_functions.h
+test_suite.o: test_suite.cpp test_suite.h string_functions.h
diff --git a/main.cpp b/main.cpp
index 7bde5e8..d434ccd 100644
--- a/main.cpp
+++ b/main.cpp
@@ -1,13 +1,23 @@
 /**
  * @file main.cpp
  * @author Tyler Beckman (tyler_beckman@mines.edu)
- * @brief A program template for CSCI200
+ * @brief CSCI200 L3B - A program to test different string modification APIs in C++
  * @version 1
  * @date 2024-09-21
  */
 
 #include <iostream>
 
-int main(void) {
-	std::cout << "Hello World" << std::endl;
-}
+#include "test_suite.h"
+
+int main() {
+
+    std::cout << "Testing your functions..." << std::endl << std::endl;
+    if( run_all_tests() ) {
+        std::cout << "ALL TESTS PASSED!" << std::endl;
+    } else {
+        std::cout << "Not all tests are passing, errors remain..." << std::endl;
+    }
+
+    return 0;
+}
\ No newline at end of file
diff --git a/main.o b/main.o
new file mode 100644
index 0000000..5526e69
Binary files /dev/null and b/main.o differ
diff --git a/string_functions.cpp b/string_functions.cpp
new file mode 100644
index 0000000..7716abb
--- /dev/null
+++ b/string_functions.cpp
@@ -0,0 +1,144 @@
+#include "string_functions.h"
+
+#include <iostream>
+
+using namespace std;
+
+unsigned long string_length(const string STR)  {
+    unsigned long result = -1;
+    result = STR.length();  // set result to the length of the string
+    return result;
+}
+
+char string_char_at(const string STR, const int IDX) {
+    char result = '\0';
+    result = STR.at(IDX);
+    std::cout << "TODO: implement string_char_at(\"" << STR << "\", " << IDX << ")" << std::endl;
+    return result;
+}
+
+string string_append(const string LEFT, const string RIGHT)  {
+    string result = LEFT;
+    result = LEFT + RIGHT;
+    std::cout << "TODO: implement string_append(\"" << LEFT << "\", \"" << RIGHT << "\")" << std::endl;
+    return result;
+}
+
+string string_insert(const string STR, const string TO_INSERT, const int IDX) {
+    string result = STR;
+    result.insert(IDX, TO_INSERT);
+    std::cout << "TODO: implement string_insert(\"" << STR << "\", \"" << TO_INSERT << "\", " << IDX << ")" << std::endl;
+    return result;
+}
+
+size_t string_find(const string STR, const char C)  {
+    size_t result = 0;
+    result = STR.find_first_of(C);
+    std::cout << "TODO: implement string_find(\"" << STR << "\", '" << C << "')" << std::endl;
+    return result;
+}
+
+string string_substring(const string STR, const int IDX, const int LEN) {
+    string result = STR;
+    result = STR.substr(IDX, LEN);
+    std::cout << "TODO: implement string_substring(\"" << STR << "\", " << IDX << ", " << LEN << ")" << std::endl;
+    return result;
+}
+
+string string_replace(const string STR, const string TEXT_TO_REPLACE, const string REPLACE_WITH) {
+    string result = STR;
+    auto index = STR.find(TEXT_TO_REPLACE);
+    if (index != -1ul) {
+        result.replace(STR.find(TEXT_TO_REPLACE), TEXT_TO_REPLACE.length(), REPLACE_WITH);
+    }
+    std::cout << "TODO: implement string_replace(\"" << STR << "\", \"" << TEXT_TO_REPLACE << "\", \"" << REPLACE_WITH << ")\"" << std::endl;
+    return result;
+}
+
+string string_first_word(const string STR)  {
+    string result = STR;
+    result = STR.substr(0, STR.find_first_of(' '));
+    std::cout << "TODO: implement string_first_word(\"" << STR << "\")" << std::endl;
+    return result;
+}
+
+string string_remove_first_word(const string STR)  {
+    string result = STR;
+    // TODO 08: set result to be the string with the first word removed
+    std::cout << "TODO: implement string_remove_first_word(\"" << STR << ")\"" << std::endl;
+    return result;
+}
+
+string string_second_word(const string STR)  {
+    string result = STR;
+    // TODO 09: set result to be the second word from the string
+    std::cout << "TODO: implement string_second_word(\"" << STR << "\")" << std::endl;
+    return result;
+}
+
+string string_third_word(const string STR)  {
+    string result = STR;
+    // TODO 10: set result to be the third word from the string
+    std::cout << "TODO: implement string_third_word(\"" << STR << "\")" << std::endl;
+    return result;
+}
+
+string string_nth_word(const string STR, const int N)  {
+    string result = STR;
+    // TODO 11: set result to be the nth word from the string
+    std::cout << "TODO: implement string_nth_word(\"" << STR << "\", " << N << ")" << std::endl;
+    return result;
+}
+
+vector<string> string_tokenize(const string STR, const char DELIMINATOR) {
+    vector<string> result;
+    // TODO 12: split the string by the given deliminator
+    std::cout << "TODO: implement string_tokenize(\"" << STR << "\", '" << DELIMINATOR << "')" << std::endl;
+    return result;
+}
+
+string string_substitute(const string STR, const char TARGET, const char REPLACEMENT)  {
+    string result = STR;
+    // TODO 13: set result to be the string with all instances of TARGET replaced
+    std::cout << "TODO: implement string_substitute(\"" << STR << "\", '" << TARGET << "', '" << REPLACEMENT << "')" << std::endl;
+    return result;
+}
+
+string string_to_lower(const string STR) {
+    string result = STR;
+    for (unsigned int i = 0; i < STR.length(); i++) {
+        char newChar = STR[i];
+        if (newChar >= 'A' && newChar <= 'Z') {
+            newChar = (char) (newChar + 32);
+        }
+        result[i] = newChar;
+    }
+    std::cout << "TODO: implement string_to_lower(\"" << STR << "\")" << std::endl;
+    return result;
+}
+
+string string_to_upper(const string STR) {
+    string result = STR;
+    for (unsigned int i = 0; i < STR.length(); i++) {
+        char newChar = STR[i];
+        if (newChar >= 'a' && newChar <= 'z') {
+            newChar = (char) (newChar - 32);
+        }
+        result[i] = newChar;
+    }
+    std::cout << "TODO: implement string_to_upper(\"" << STR << "\")" << std::endl;
+    return result;
+}
+
+int string_compare(const string LHS, const string RHS) {
+    int result = 0;
+    if (LHS > RHS) {
+        result = 1;
+    } else {
+        if (LHS < RHS) {
+            result = -1;
+        }
+    }
+    std::cout << "TODO: implement string_compare(\"" << LHS << "\", \"" << RHS << "\")" << std::endl;
+    return result;
+}
\ No newline at end of file
diff --git a/string_functions.h b/string_functions.h
new file mode 100644
index 0000000..fb0e298
--- /dev/null
+++ b/string_functions.h
@@ -0,0 +1,145 @@
+#ifndef STRING_FUNCTIONS_H
+#define STRING_FUNCTIONS_H
+
+#include <string>
+#include <vector>
+
+/**
+ * @brief Returns the length of a string
+ * @param STR string to return the length of
+ * @return length of the input string
+ */
+unsigned long string_length(const std::string STR);
+
+/**
+ * @brief Returns the character of a string at a given index
+ * @param STR full string
+ * @param IDX index to access string at
+ * @return character from STR at index IDX
+ */
+char string_char_at(const std::string STR, const int IDX);
+
+/**
+ * @brief Returns a concatenation of strings left and right
+ * @param LEFT string to be appended to
+ * @param RIGHT string to be appended
+ * @return concatenated string LEFTRIGHT
+ */
+std::string string_append(const std::string LEFT, const std::string RIGHT);
+
+/**
+ * @brief Returns the result of inserting a string into another at a given position
+ * @param STR original string
+ * @param TO_INSERT string to be inserted into STR
+ * @param IDX location within STR to insert TO_INSERT
+ * @return a new string with TO_INSERT inserted at index IDX of STR
+ */
+std::string string_insert(const std::string STR, const std::string TO_INSERT, const int IDX);
+
+/**
+ * @brief Returns the first index of a character in a string
+ * @param STR string to search within (the haystack)
+ * @param C character to search for (the needle)
+ * @return if found, first position within STR that C is located.  otherwise returns string::npos
+ */
+size_t string_find(const std::string STR, const char C);
+
+/**
+ * @brief Returns part of a string
+ * @param STR original full string
+ * @param IDX starting position to return a substring from
+ * @param LEN length of substring to return
+ * @return a substring of length LEN from STR
+ */
+std::string string_substring(const std::string STR, const int IDX, const int LEN);
+
+/**
+ * @brief Replaces part of a string
+ * @param STR original full string (the haystack)
+ * @param TEXT_TO_REPLACE the existing text to replace (the needle)
+ * @param REPLACE_WITH the new text to insert
+ * @return modified string (if text found), otherwise the original string
+ */
+std::string string_replace(const std::string STR, const std::string TEXT_TO_REPLACE, const std::string REPLACE_WITH);
+
+/**
+ * @brief Returns the first word, given a sentence
+ * @param STR original full string
+ * @return substring up to the first whitespace
+ */
+std::string string_first_word(const std::string STR);
+
+/**
+ * @brief Returns the string with the first word removed
+ * @param STR original full string
+ * @return substring after the first whitespace
+ */
+std::string string_remove_first_word(const std::string STR);
+
+/**
+ * @brief Returns the second word, given a sentence
+ * @param STR original full string
+ * @return substring after the first whitespace up to the second whitespace
+ */
+std::string string_second_word(const std::string STR);
+
+/**
+ * @brief Returns the third word, given a sentence
+ * @param STR original full string
+ * @return substring after the second whitespace up to the third whitespace
+ */
+std::string string_third_word(const std::string STR);
+
+/**
+ * @brief Returns the nth word, given a sentence
+ * @param STR original full string
+ * @param N word within STR to return (beginning at 1)
+ * @return corresponding word from STR
+ */
+std::string string_nth_word(const std::string STR, const int N);
+
+/**
+ * @brief Splits a string into a list of tokens deliminated by a given character
+ * 
+ * @param STR string to tokenize
+ * @param DELIMINATOR character to split on
+ * @return vector<string> list of all tokens in the order present in the original string
+ */
+std::vector<std::string> string_tokenize(const std::string STR, const char DELIMINATOR);
+
+/**
+ * @brief Returns a string substituting target character with replacement character
+ * @param STR original full string (the haystack)
+ * @param TARGET character to replace (the needle)
+ * @param REPLACEMENT character to substitute with
+ * @return string with all instance of TARGET replaced with REPLACEMENT
+ */
+std::string string_substitute(const std::string STR, const char TARGET, const char REPLACEMENT);
+
+/**
+ * @brief Returns a string with all uppercase characters converted to lowercase characters
+ * 
+ * @param STR original string
+ * @return string with lowercase characters
+ */
+std::string string_to_lower(const std::string STR);
+
+/**
+ * @brief Returns a string with all lowercase characters converted to uppercase characters
+ * 
+ * @param STR original string
+ * @return string with uppercase characters
+ */
+std::string string_to_upper(const std::string STR);
+
+/**
+ * @brief Compares two strings to determine their ordering or equality.  Returns -1 if 
+ * LHS < RHS.  Returns 0 if LHS == RHS.  Returns 1 if LHS > RHS
+ * 
+ * @param LHS left hand string
+ * @param RHS right hand string
+ * @return int representing relationship of LHS to RHS
+ */
+int string_compare(const std::string LHS, const std::string RHS);
+
+#endif
\ No newline at end of file
diff --git a/string_functions.o b/string_functions.o
new file mode 100644
index 0000000..84faf86
Binary files /dev/null and b/string_functions.o differ
diff --git a/test_suite.cpp b/test_suite.cpp
new file mode 100644
index 0000000..98196d2
--- /dev/null
+++ b/test_suite.cpp
@@ -0,0 +1,256 @@
+#include "test_suite.h"
+#include "string_functions.h"
+
+#include <iomanip>
+#include <iostream>
+
+using namespace std;
+
+const int MESSAGE_WIDTH = 45;
+
+int test_int(int& testNum, const string MESSAGE, const int LHS, const int RHS)  {
+    cout << "Test #" << setw(3) << right << ++testNum;
+    cout << setw(MESSAGE_WIDTH) << right;
+    cout << MESSAGE << ": ";
+    cout << left;
+    if (LHS == RHS)
+        cout << "    PASSED   \n";
+    else
+        cout << " !!>FAILED<!! Returned: \"" << LHS << "\" != Expected: \"" << RHS << "\"\n";
+    return LHS == RHS ? 1 : 0;
+}
+
+int test_size_t(int& testNum, const string MESSAGE, const size_t LHS, const size_t RHS)  {
+    cout << "Test #" << setw(3) << right << ++testNum;
+    cout << setw(MESSAGE_WIDTH) << right;
+    cout << MESSAGE << ": ";
+    cout << left;
+    if (LHS == RHS)
+        cout << "    PASSED   \n";
+    else
+        cout << " !!>FAILED<!! Returned: \"" << LHS << "\" != Expected: \"" << RHS << "\"\n";
+    return LHS == RHS ? 1 : 0;
+}
+
+int test_char(int& testNum, const string MESSAGE, const char LHS, const char RHS)  {
+    cout << "Test #" << setw(3) << right << ++testNum;
+    cout << setw(MESSAGE_WIDTH) << right;
+    cout << MESSAGE << ": ";
+    cout << left;
+    if (LHS == RHS)
+        cout << "    PASSED   \n";
+    else
+        cout << " !!>FAILED<!! Returned: \"" << LHS << "\" != Expected: \"" << RHS << "\"\n";
+    return LHS == RHS ? 1 : 0;
+}
+
+int test_string(int& testNum, const string MESSAGE, const string LHS, const string RHS)  {
+    cout << "Test #" << setw(3) << right << ++testNum;
+    cout << setw(MESSAGE_WIDTH) << right;
+    cout << MESSAGE << ": ";
+    cout << left;
+    if (LHS == RHS)
+        cout << "    PASSED   \n";
+    else
+        cout << " !!>FAILED<!! Returned: \"" << LHS << "\" != Expected: \"" << RHS << "\"\n";
+    return LHS == RHS ? 1 : 0;
+}
+
+int test_vector_string(int& testNum, const string MESSAGE, const vector<string>& LHS, const vector<string>& RHS) {
+    cout << "Test #" << setw(3) << right << ++testNum;
+    cout << setw(MESSAGE_WIDTH) << right;
+    cout << MESSAGE << ": ";
+    cout << left;
+
+    bool vectorsMatch = (LHS.size() == RHS.size());
+    if (vectorsMatch) {
+        for(unsigned int i = 0; i < LHS.size(); i++) {
+            if(LHS.at(i) != RHS.at(i)) {
+                vectorsMatch = false;
+                break;
+            }
+        }
+    }
+    if (vectorsMatch) {
+        cout << "    PASSED   \n";
+    } else {
+        cout << " !!>FAILED<!! Returned: {";
+        for(unsigned int i = 0; i < LHS.size(); i++) {
+            cout << "\"" << LHS.at(i) << "\"";
+            if(i < LHS.size() - 1) {
+                cout << ", ";
+            }
+        }
+        cout << "} != Expected: {";
+        for(unsigned int i = 0; i < RHS.size(); i++) {
+            cout << "\"" << RHS.at(i) << "\"";
+            if(i < RHS.size() - 1) {
+                cout << ", ";
+            }
+        }
+        cout << "}\n";
+    }
+    return vectorsMatch ? 1 : 0;
+}
+
+bool run_all_tests()  {
+    int totalPassed = 0, totalNumTests = 0;
+    totalPassed += test_size_t(        totalNumTests,  "Testing string_length()",              string_length("Now") , 3 );
+    totalPassed += test_size_t(        totalNumTests,  "Testing string_length()",              string_length("Tablet") , 6 );
+    totalPassed += test_size_t(        totalNumTests,  "Testing string_length()",              string_length("The length is 17.") , 17 );
+    totalPassed += test_size_t(        totalNumTests,  "Testing string_length()",              string_length("A") , 1 );
+    totalPassed += test_size_t(        totalNumTests,  "Testing string_length()",              string_length("") , 0 );
+    cout << endl;
+
+    totalPassed += test_char(          totalNumTests,  "Testing string_char_at()",             string_char_at("Elephant", 3) , 'p' );
+    totalPassed += test_char(          totalNumTests,  "Testing string_char_at()",             string_char_at("Giraffe", 2) , 'r' );
+    totalPassed += test_char(          totalNumTests,  "Testing string_char_at()",             string_char_at("Armadillo", 4) , 'd' );
+    cout << endl;
+
+    totalPassed += test_string(        totalNumTests,  "Testing string_append()",              string_append("There's a ", "natural mystic.") , "There's a natural mystic." );
+    totalPassed += test_string(        totalNumTests,  "Testing string_append()",              string_append("It's the ", "eye of the tiger.") , "It's the eye of the tiger." );
+    totalPassed += test_string(        totalNumTests,  "Testing string_append()",              string_append("Some", "thing") , "Something" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_append()",              string_append("", "Nothing to something.") , "Nothing to something." );
+    totalPassed += test_string(        totalNumTests,  "Testing string_append()",              string_append("Not adding anything.", "") , "Not adding anything." );
+    totalPassed += test_string(        totalNumTests,  "Testing string_append()",              string_append("", "") , "" );
+    cout << endl;
+
+    totalPassed += test_string(        totalNumTests,  "Testing string_insert()",              string_insert("If you carefully.", "listen ", 7) , "If you listen carefully." );
+    totalPassed += test_string(        totalNumTests,  "Testing string_insert()",              string_insert("carefully.", "Watch ", 0) , "Watch carefully." );
+    totalPassed += test_string(        totalNumTests,  "Testing string_insert()",              string_insert("Iner", "t", 2) , "Inter" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_insert()",              string_insert("", "TA DA!", 0) , "TA DA!" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_insert()",              string_insert("TA DA!", "", 0) , "TA DA!" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_insert()",              string_insert("", "", 0) , "" );
+    cout << endl;
+
+    totalPassed += test_size_t(        totalNumTests,  "Testing string_find()",                string_find("Have to face reality now.", 'o') , 6 );
+    totalPassed += test_size_t(        totalNumTests,  "Testing string_find()",                string_find("Have to face reality now.", 'e') , 3 );
+    totalPassed += test_size_t(        totalNumTests,  "Testing string_find()",                string_find("Have to face reality now.", 'r') , 13 );
+    totalPassed += test_size_t(        totalNumTests,  "Testing string_find()",                string_find("Have to face reality now.", 'a') , 1 );
+    totalPassed += test_size_t(        totalNumTests,  "Testing string_find()",                string_find("Have to face reality now.", 'q') , string::npos );
+    totalPassed += test_size_t(        totalNumTests,  "Testing string_find()",                string_find("Have to face reality now.", 'h') , string::npos );
+    totalPassed += test_size_t(        totalNumTests,  "Testing string_find()",                string_find("", '?') , string::npos );
+    cout << endl;
+
+    totalPassed += test_string(        totalNumTests,  "Testing string_substring()",           string_substring("Such a natural mystic", 7, 7) , "natural" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_substring()",           string_substring("Such a natural mystic", 8, 2) , "at" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_substring()",           string_substring("Such a natural mystic", 0, 4) , "Such" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_substring()",           string_substring("Something to nothing.", 0, 0) , "" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_substring()",           string_substring("Something to nothing.", 10, 0) , "" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_substring()",           string_substring("", 0, 0) , "" );
+    cout << endl;
+
+    totalPassed += test_string(        totalNumTests,  "Testing string_replace()",             string_replace("Strings are not the way", "Strings", "Things") , "Things are not the way" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_replace()",             string_replace("Strings are not the way", "not the", "the") , "Strings are the way" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_replace()",             string_replace("Show me the things", "things", "way") , "Show me the way" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_replace()",             string_replace("Show me the things", "car", "way") , "Show me the things" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_replace()",             string_replace("Show me the things", "the ", "") , "Show me things" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_replace()",             string_replace("", "now what?", "hmm") , "" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_replace()",             string_replace("", "now", "") , "" );
+    cout << endl;
+
+    totalPassed += test_string(        totalNumTests,  "Testing string_first_word()",          string_first_word("The quick brown fox jumped over the lazy dog") , "The" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_first_word()",          string_first_word("A man a plan a canal Panama") , "A" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_first_word()",          string_first_word("I have the hang of this") , "I" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_first_word()",          string_first_word("Testing string_first_word()") , "Testing" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_first_word()",          string_first_word("Single") , "Single" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_first_word()",          string_first_word("Uh oh") , "Uh" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_first_word()",          string_first_word("") , "" );
+    cout << endl;
+
+    totalPassed += test_string(        totalNumTests,  "Testing string_remove_first_word()",   string_remove_first_word("The quick brown fox jumped over the lazy dog") , "quick brown fox jumped over the lazy dog" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_remove_first_word()",   string_remove_first_word("Testing string_remove_first_word()") , "string_remove_first_word()" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_remove_first_word()",   string_remove_first_word("Goodbye") , "" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_remove_first_word()",   string_remove_first_word("") , "" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_remove_first_word() twice",string_remove_first_word(string_remove_first_word("The quick brown fox jumped over the lazy dog")) , "brown fox jumped over the lazy dog" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_remove_first_word() twice",string_remove_first_word("Testing string_remove_first_word()") , "" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_remove_first_word() twice",string_remove_first_word(string_remove_first_word("Goodbye")) , "" );
+    cout << endl;
+
+    totalPassed += test_string(        totalNumTests,  "Testing string_second_word()",         string_second_word("The quick brown fox jumped over the lazy dog") , "quick" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_second_word()",         string_second_word("A man a plan a canal Panama") , "man" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_second_word()",         string_second_word("Testing string_second_word()") , "string_second_word()" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_second_word()",         string_second_word("I have the hang of this") , "have" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_second_word()",         string_second_word("Uh oh") , "oh" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_second_word()",         string_second_word("Single") , "" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_second_word()",         string_second_word("") , "" );
+    cout << endl;
+
+    totalPassed += test_string(        totalNumTests,  "Testing string_third_word()",          string_third_word("The quick brown fox jumped over the lazy dog") , "brown" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_third_word()",          string_third_word("A man a plan a canal Panama") , "a" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_third_word()", 	       string_third_word("I have the hang of this") , "the" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_third_word()", 	       string_third_word("Uh oh no") , "no" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_third_word()", 	       string_third_word("Uh oh") , "" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_third_word()", 	       string_third_word("Single") , "" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_third_word()", 	       string_third_word("") , "" );
+    cout << endl;
+
+    totalPassed += test_string(        totalNumTests,  "Testing string_nth_word(1)",           string_nth_word("The quick brown fox jumped over the lazy dog", 1) , "The" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_nth_word(2)",           string_nth_word("The quick brown fox jumped over the lazy dog", 2) , "quick" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_nth_word(3)",           string_nth_word("The quick brown fox jumped over the lazy dog", 3) , "brown" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_nth_word(4)",           string_nth_word("The quick brown fox jumped over the lazy dog", 4) , "fox" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_nth_word(5)",           string_nth_word("The quick brown fox jumped over the lazy dog", 5) , "jumped" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_nth_word(6)",           string_nth_word("The quick brown fox jumped over the lazy dog", 6) , "over" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_nth_word(7)",           string_nth_word("The quick brown fox jumped over the lazy dog", 7) , "the" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_nth_word(8)",           string_nth_word("The quick brown fox jumped over the lazy dog", 8) , "lazy" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_nth_word(9)",           string_nth_word("The quick brown fox jumped over the lazy dog", 9) , "dog" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_nth_word(10)",          string_nth_word("The quick brown fox jumped over the lazy dog", 10) , "" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_nth_word(11)",          string_nth_word("The quick brown fox jumped over the lazy dog", 11) , "" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_nth_word(1)",           string_nth_word("", 1) , "" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_nth_word(2)",           string_nth_word("", 2) , "" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_nth_word(3)",           string_nth_word("", 3) , "" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_nth_word(10)",          string_nth_word("", 10) , "" );
+    cout << endl;
+
+    vector<string> tokens1 = {"The", "quick", "brown", "fox", "jumped", "over", "the", "lazy", "dog"};
+    totalPassed += test_vector_string( totalNumTests,  "Testing string_tokenize()",            string_tokenize("The quick brown fox jumped over the lazy dog", ' '), tokens1 );
+    totalPassed += test_vector_string( totalNumTests,  "Testing string_tokenize()",            string_tokenize("The@quick@brown@fox@jumped@over@the@lazy@dog", '@'), tokens1 );
+
+    vector<string> tokens2 = {"The quick brown fox jumped over the lazy dog"};
+    totalPassed += test_vector_string( totalNumTests,  "Testing string_tokenize()",            string_tokenize("The quick brown fox jumped over the lazy dog", '*'), tokens2 );
+    
+    vector<string> tokens3 = {""};
+    totalPassed += test_vector_string( totalNumTests,  "Testing string_tokenize()",            string_tokenize("", '*'), tokens3 );
+    cout << endl;
+
+    totalPassed += test_string(        totalNumTests,  "Testing string_substitute()",          string_substitute("The Gxxgle", 'x', 'o') , "The Google" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_substitute()",          string_substitute("$chool of Mine$", '$', 's') , "school of Mines" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_substitute()",          string_substitute("$chool of Mine$", '+', '*') , "$chool of Mine$" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_substitute() twice",    string_substitute(string_substitute("D--", '-', '+'), 'D', 'C') , "C++" );
+    cout << endl;
+
+    totalPassed += test_string(        totalNumTests,  "Testing string_to_lower()",            string_to_lower("This SHOULD be LOWER case") , "this should be lower case" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_to_lower()",            string_to_lower("MNASDF874792L[]//.;[\t],") , "mnasdf874792l[]//.;[\t]," );
+    totalPassed += test_string(        totalNumTests,  "Testing string_to_lower()",            string_to_lower("C++") , "c++" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_to_lower()",            string_to_lower("this is already lower case") , "this is already lower case" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_to_lower()",            string_to_lower("1234567890,./;'[]") , "1234567890,./;'[]" );
+    cout << endl;
+
+    totalPassed += test_string(        totalNumTests,  "Testing string_to_upper()",            string_to_upper("This SHOULD be upper case") , "THIS SHOULD BE UPPER CASE" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_to_upper()",            string_to_upper("mnasdf874792l[]//.;[\t],") , "MNASDF874792L[]//.;[\t]," );
+    totalPassed += test_string(        totalNumTests,  "Testing string_to_upper()",            string_to_upper("c++") , "C++" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_to_upper()",            string_to_upper("THIS IS ALREADY UPPER CASE") , "THIS IS ALREADY UPPER CASE" );
+    totalPassed += test_string(        totalNumTests,  "Testing string_to_upper()",            string_to_upper("1234567890,./;'[]") , "1234567890,./;'[]" );
+    cout << endl;
+
+    totalPassed += test_int(           totalNumTests,  "Testing string_compare()",             string_compare("C++", "c++") , -1 );
+    totalPassed += test_int(           totalNumTests,  "Testing string_compare()",             string_compare("C++", "C++") , 0 );
+    totalPassed += test_int(           totalNumTests,  "Testing string_compare()",             string_compare("c++", "c++") , 0 );
+    totalPassed += test_int(           totalNumTests,  "Testing string_compare()",             string_compare("c++", "C++") , 1 );
+    totalPassed += test_int(           totalNumTests,  "Testing string_compare()",             string_compare("short", "shorter") , -1 );
+    totalPassed += test_int(           totalNumTests,  "Testing string_compare()",             string_compare("longer", "long") , 1 );
+    totalPassed += test_int(           totalNumTests,  "Testing string_compare()",             string_compare("after", "later") , -1 );
+    totalPassed += test_int(           totalNumTests,  "Testing string_compare()",             string_compare("later", "after") , 1 );
+    totalPassed += test_int(           totalNumTests,  "Testing string_compare()",             string_compare("G", "g") , -1 );
+    totalPassed += test_int(           totalNumTests,  "Testing string_compare()",             string_compare("g", "G") , 1 );
+    totalPassed += test_int(           totalNumTests,  "Testing string_compare()",             string_compare("GoOse", "Bye") , 1 );
+    totalPassed += test_int(           totalNumTests,  "Testing string_compare()",             string_compare("Equal", "Equal") , 0 );
+    totalPassed += test_int(           totalNumTests,  "Testing string_compare()",             string_compare("Not Empty", "") , 1 );
+    totalPassed += test_int(           totalNumTests,  "Testing string_compare()",             string_compare("", "Not Empty") , -1 );
+    totalPassed += test_int(           totalNumTests,  "Testing string_compare()",             string_compare("", "") , 0 );
+    cout << endl;
+
+    cout << "Tests Passed: " << setw(3) << right << totalPassed << " / " << setw(3) << totalNumTests << " (" << setprecision(0) << fixed << totalPassed * 100.0f / totalNumTests << "%)" << endl << endl;
+    
+    return (totalPassed == totalNumTests);
+}
\ No newline at end of file
diff --git a/test_suite.h b/test_suite.h
new file mode 100644
index 0000000..9d0695a
--- /dev/null
+++ b/test_suite.h
@@ -0,0 +1,73 @@
+#ifndef TEST_SUITE_H
+#define TEST_SUITE_H
+
+#include <string>
+#include <vector>
+
+/** 
+ * @brief Test suite. Runs all tests.
+ * @return true if all tests pass, false otherwise
+ */
+bool run_all_tests();
+
+/**
+ * @brief A generic test function, that simply prints "PASSED" if LHS equals RHS 
+ * and otherwise prints FAILED. Do not modify this function.
+ * 
+ * @param testNum Number of the test.  Value will be incremented upon completion
+ * @param MESSAGE description of test
+ * @param LHS computed result
+ * @param RHS expected result
+ * @return 1 if test passed, 0 otherwise
+ */
+int test_int(int& testNum, const std::string MESSAGE, const int LHS, const int RHS);
+
+/**
+ * @brief A generic test function, that simply prints "PASSED" if LHS equals RHS 
+ * and otherwise prints FAILED. Do not modify this function.
+ * 
+ * @param testNum Number of the test.  Value will be incremented upon completion
+ * @param MESSAGE description of test
+ * @param LHS computed result
+ * @param RHS expected result
+ * @return 1 if test passed, 0 otherwise
+ */
+int test_unsigned_long(int& testNum, const std::string MESSAGE, const unsigned long LHS, const unsigned long RHS);
+
+/**
+ * @brief A generic test function, that simply prints "PASSED" if LHS equals RHS 
+ * and otherwise prints FAILED. Do not modify this function.
+ * 
+ * @param testNum Number of the test.  Value will be incremented upon completion
+ * @param MESSAGE description of test
+ * @param LHS computed result
+ * @param RHS expected result
+ * @return 1 if test passed, 0 otherwise
+ */
+int test_char(int& testNum, const std::string MESSAGE, const char LHS, const char RHS);
+
+/**
+ * @brief A generic test function, that simply prints "PASSED" if LHS equals RHS 
+ * and otherwise prints FAILED. Do not modify this function.
+ * 
+ * @param testNum Number of the test.  Value will be incremented upon completion
+ * @param MESSAGE description of test
+ * @param LHS computed result
+ * @param RHS expected result
+ * @return 1 if test passed, 0 otherwise
+ */
+int test_string(int& testNum, const std::string MESSAGE, const std::string LHS, const std::string RHS);
+
+/**
+ * @brief A generic test function, that simply prints "PASSED" if LHS equals RHS 
+ * and otherwise prints FAILED. Do not modify this function.
+ * 
+ * @param testNum Number of the test.  Value will be incremented upon completion
+ * @param MESSAGE description of test
+ * @param LHS computed result
+ * @param RHS expected result
+ * @return 1 if test passed, 0 otherwise
+ */
+int test_vector_string(int& testNum, const std::string MESSAGE, const std::vector<std::string>& LHS, const std::vector<std::string>& RHS);
+
+#endif
\ No newline at end of file
diff --git a/test_suite.o b/test_suite.o
new file mode 100644
index 0000000..ed0c86f
Binary files /dev/null and b/test_suite.o differ