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Write one line functions for strcat() and strcmp()

  • Difficulty Level : Hard
  • Last Updated : 31 Jul, 2018

Recursion can be used to do both tasks in one line. Below are one line implementations for stracat() and strcmp().




/* my_strcat(dest, src) copies data of src to dest.  To do so, it first reaches end of the string dest using recursive calls my_strcat(++dest, src).  Once end of dest is reached, data is copied using 
(*dest++ = *src++)?  my_strcat(dest, src). */
void my_strcat(char *dest, char *src)
{
  (*dest)? my_strcat(++dest, src): (*dest++ = *src++)? my_strcat(dest, src): 0 ;
}
  
/* driver function to test above function */
int main()
{
  char dest[100] = "geeksfor";
  char *src = "geeks";
  my_strcat(dest, src);
  printf(" %s ", dest);
  getchar();
}    

The function my_strcmp() is simple compared to my_strcmp().




/* my_strcmp(a, b) returns 0 if strings a and b are same, otherwise 1.   It recursively increases a and b pointers. At any point if *a is not equal to *b then 1 is returned.  If we reach end of both strings at the same time then 0 is returned. */
int my_strcmp(char *a, char *b)
{
  return (*a == *b && *b == '\0')? 0 : (*a == *b)? my_strcmp(++a, ++b): 1;
  
/* driver function to test above function */
int main()
{
  char *a = "geeksforgeeks";
  char *b = "geeksforgeeks";
  if(my_strcmp(a, b) == 0)
     printf(" String are same ");
  else  
     printf(" String are not same ");  
  
  getchar();
  return 0;
}    

The above functions do very basic string concatenation and string comparison. These functions do not provide same functionality as standard library functions.

Please write comments if you find the above code incorrect, or find better ways to solve the same problem.

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