Question

Can any one explain what algorithm used in strcmp to compare two string in C programming ?

I didnt understand the return value from this, It uses any algorithm like ‘Levenstien algorithm‘ to find out distance between two string…

Answer 1

The GNU implementation of the standard C library, glibc, is open source and you can just read strcmp.c if you are curious. There is not much to it. Here it is:

/* Compare S1 and S2, returning less than, equal to or
   greater than zero if S1 is lexicographically less than,
   equal to or greater than S2.  */
int strcmp (const char *p1, const char *p2)
{
  register const unsigned char *s1 = (const unsigned char *) p1;
  register const unsigned char *s2 = (const unsigned char *) p2;
  unsigned reg_char c1, c2;

  do
    {
      c1 = (unsigned char) *s1++;
      c2 = (unsigned char) *s2++;
      if (c1 == '\0')
        return c1 - c2;
    }
  while (c1 == c2);

  return c1 - c2;
}