core/strncasecmp.c

   1 /*
   2  * strncasecmp.c
   3  */
   4
   5 #include <string.h>
   6 #include <ctype.h>
   7
   8 int strncasecmp(const char *s1, const char *s2, size_t n)
   9 {
  10     const unsigned char *c1 = (const unsigned char *)s1;
  11     const unsigned char *c2 = (const unsigned char *)s2;
  12     unsigned char ch;
  13     int d = 0;
  14
  15     while (n--) {
  16         /* toupper() expects an unsigned char (implicitly cast to int)
  17            as input, and returns an int, which is exactly what we want. */
  18         d = toupper(ch = *c1++) - toupper(*c2++);
  19         if (d || !ch)
  20             break;
  21     }
  22
  23     return d;
  24 }