sds sdscpylen(sds s, const char *t, size_t len) {
struct sdshdr *sh = (void*) (s-(sizeof(struct sdshdr)));
size_t totlen = sh->free+sh->len;
if (totlen < len) {//判断原字符串的长度是否比len小
s = sdsMakeRoomFor(s,len-sh->len);
if (s == NULL) return NULL;
sh = (void*) (s-(sizeof(struct sdshdr)));
totlen = sh->free+sh->len;
}
memcpy(s, t, len);
s[len] = '\0';
sh->len = len;
sh->free = totlen-len;
return s;
}
将t指向的字符串复制到字符串s中,其中s字符串是sds类型的,且长度为len。
sds sdscpy(sds s, const char *t) {
return sdscpylen(s, t, strlen(t));
}
功能和sdscpylen()一样,但不同的是:t必须以空结尾,这样便于strlen()来计算其长度。