Function stbi__pnm_isdigit

lite/example/cpp_example/mge/cv/stb_image.h:8261–8263

}

static int stbi__pnm_isdigit(char c) {
    return c >= '0' && c <= '9';
}

static int stbi__pnm_getinteger(stbi__context* s, char* c) {
    int value = 0;