不同的strcmp

Android libc中的strcmp
https://android.googlesource.com/platform/bootable/bootloader/legacy/+/donut-release/libc/strcmp.c
int strcmp(const char *a, const char *b)
{
　　while(*a && *b) {
　　if(*a++ != *b++) return 1;
　　}
　　if(*a || *b) return 1;
　　return 0;
}

ios中libc中的strcmp
http://www.opensource.apple.com/source/Libc/Libc-262/ppc/gen/strcmp.c
int strcmp(const char *s1, const char *s2)
{
　　for ( ; *s1 == *s2; s1++, s2++)
　　if (*s1 == '\0')
　　return 0;
　　return ((*(unsigned char *)s1 < *(unsigned char *)s2) ? -1 : +1);
}