C语言中如何重复一个字符串

我该如何重复一个字符串？ 类似“你好世界”* 3 输出“你好世界你好世界你好世界”

在您的源代码中，无需太多处理，最简单的方法可能是：

#define HI "hello world"
char str[] = HI " " HI " " HI;

这将声明请求值的字符串：

"hello world hello world hello world"

如果你想code这样就可以了，你可以使用类似的东西：

char *repeatStr (char *str, size_t count) {
    if (count == 0) return NULL;
    char *ret = malloc (strlen (str) * count + count);
    if (ret == NULL) return NULL;
    strcpy (ret, str);
    while (--count > 0) {
        strcat (ret, " ");
        strcat (ret, str);
    }
    return ret;
}

Now keep in mind this can be made more efficient - multiple strcat operations are ripe for optimisation to avoid processing the data over and over ^(a). But this should be a good enough start.

您还负责释放此函数返回的内存。

^(a) Such as with:

// Like strcat but returns location of the null terminator
//   so that the next myStrCat is more efficient.

char *myStrCat (char *s, char *a) {
    while (*s != '\0') s++;
    while (*a != '\0') *s++ = *a++;
    *s = '\0';
    return s;
}

char *repeatStr (char *str, size_t count) {
    if (count == 0) return NULL;
    char *ret = malloc (strlen (str) * count + count);
    if (ret == NULL) return NULL;
    *ret = '\0';
    char *tmp = myStrCat (ret, str);
    while (--count > 0) {
        tmp = myStrCat (tmp, " ");
        tmp = myStrCat (tmp, str);
    }
    return ret;
}