knr/5.3.c

/* strcat:  concatenate t to end of s */

#include <stdio.h>
void strcat(char s[], char t[]);
int main()
{
  char lol1[100] = "aaaa";
  char lol2[100] = "xxxx";
  printf("string 1 : %s \n",lol1);
  printf("string 2 : %s \n",lol2);
  strcat(lol1,lol2);
  printf("string 1 : %s \n",lol1);
  printf("string 2 : %s \n",lol2);
  
  return 0;
}

/* write a pointer version of the function strcat that we showed in Chapter 2: 
strcat(s,t) copies the string t to the end of s.  */

void strcat(char s[], char t[])
{
  // seek to end of s
  char* sp=s;
  while (*(sp++));
  sp--;
  do
  {
	 (*sp)=(*t);
	 sp++;
    }
  while (*(t++));
}