C++ undefined reference to defined function

Question

I cannot figure out why this is not working. I will put up all three of my files and possibly someone can tell me why it is throwing this error. I am using g++ to compile the program.

Program:

#include <iostream> #include "h8.h"  using namespace std;  int main() {   char sentence[MAX_SENTENCE_LENGTH];   char writeTo[] = "output.txt";   int distanceTo,likePosition, length, numWords;   cout << "ENTER A SENTENCE!   ";   cin.getline(sentence, 299);   length = strlen(sentence);   numWords = wordCount(sentence, length);   for(int x = 0; x < 3; ++x)   {     likePosition = likePos(numWords);     distanceTo = lengthTo(sentence, likePosition, length);     insertLike(sentence, distanceTo, length, writeTo);   }   return 0;   } 

Function file:

void insertLike(const char sentence[],  const int lengthTo, const int length, char writeTo[]) {   char part1[MAX_SENTENCE_LENGTH], part2[MAX_SENTENCE_LENGTH];   char like[] = " like ";   for(int y = 0; y < lengthTo; ++y)     part1[y] = sentence[y];   for(int z = lengthTo+1; z < length - lengthTo; ++z)     part2[z] = sentence[z];   strcat(part1, like);   strcat(part1, part2);   writeToFile(sentence, writeTo);   return; } 

Header file:

void insertLike(const char sentence[], const int lengthTo, const int length, const char writeTo[]); 

The error exactly is:

undefined reference to 'insertLike(char const*, int, int, char const*)' collect2: ld returned 1 exit status 

Answer 1

The declaration and definition of insertLike are different

In your header file:

void insertLike(const char sentence[], const int lengthTo, const int length, const char writeTo[]);

In your 'function file':

void insertLike(const char sentence[], const int lengthTo, const int length,char writeTo[]);

C++ allows function overloading, where you can have multiple functions/methods with the same name, as long as they have different arguments. The argument types are part of the function's signature.

In this case, insertLike which takes const char* as its fourth parameter and insertLike which takes char * as its fourth parameter are different functions.