UNIX 7th Ed. - /usr/src/libc/gen/atoi.c

   1: atoi(p)
   2: register char *p;
   3: {
   4:     register int n;
   5:     register int f;
   6: 
   7:     n = 0;
   8:     f = 0;
   9:     for(;;p++) {
  10:         switch(*p) {
  11:         case ' ':
  12:         case '\t':
  13:             continue;
  14:         case '-':
  15:             f++;
  16:         case '+':
  17:             p++;
  18:         }
  19:         break;
  20:     }
  21:     while(*p >= '0' && *p <= '9')
  22:         n = n*10 + *p++ - '0';
  23:     return(f? -n: n);
  24: }

Defined functions