ladybird/LibC/strings.cpp

#include <strings.h>
#include <assert.h>
#include <ctype.h>

extern "C" {

static char foldcase(char ch)
{
    if (isalpha(ch))
        return tolower(ch);
    return ch;
}

int strcasecmp(const char* s1, const char* s2)
{
    for (; foldcase(*s1) == foldcase(*s2); ++s1, ++s2) {
        if (*s1 == 0)
            return 0;
    }
    return foldcase(*(const unsigned char*)s1) < foldcase(*(const unsigned char*)s2) ? -1 : 1;
}

int strncasecmp(const char* s1, const char* s2, size_t n)
{
    if (!n)
        return 0;
    do {
        if (foldcase(*s1) != foldcase(*s2++))
            return foldcase(*(const unsigned char*)s1) - foldcase(*(const unsigned char*)--s2);
        if (*s1++ == 0)
            break;
    } while (--n);
    return 0;
}

}