C/Data Structure Algorithm/Selection Sort

#include <string.h>
#include <stdio.h>
#include <stdlib.h>
void select(char *items, int count);
int main(void) {
  char s[255];
  printf("Enter a string:");
  gets(s);
  select(s, strlen(s));
  printf("The sorted string is: %s.\n", s);
  return 0;
}
void select(char *items, int count)
{
  register int a, b, c;
  int exchange;
  char t;
  for(a = 0; a < count-1; ++a) {
    exchange = 0;
    c = a;
    t = items[ a ];
    for(b = a + 1; b < count; ++b) {
      if(items[ b ] < t) {
        c = b;
        t = items[ b ];
        exchange = 1;
      }
    }
    if(exchange) {
      items[ c ] = items[ a ];
      items[ a ] = t;
    }
  }
}