Default Arguments vs. Overloading : function overload « Function « C++ Tutorial

1. C++ Tutorial
2. Function
3. function overload

#include <iostream>
#include <cstring>
using namespace std;
   
void mystrcat(char *s1, char *s2, int len = -1);
   
int main()
{
  char str1[80] = "This is a test";
  char str2[80] = "0123456789";
   
  mystrcat(str1, str2, 5); // concatenate 5 chars
  cout << str1 << '\n';
   
  strcpy(str1, "This is a test"); // reset str1
   
  mystrcat(str1, str2); // concatenate entire string
  cout << str1 << '\n';
   
  return 0;
}
   
// A custom version of strcat().
void mystrcat(char *s1, char *s2, int len)
{
  // find end of s1
  while(*s1) s1++;
   
  if(len == -1) len = strlen(s2);
   
  while(*s2 && len) {
    *s1 = *s2; // copy chars
    s1++; 
    s2++;
    len--;
  }
 
  *s1 = '\0'; // null terminate s1
}