C Programming

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

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.


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