cJSON_AddStringToObject 添加字符串后原字符串是否可以清空？

要确定 cjson 对象保存的是指针还是字符串内容，写了如下测试代码

/*
 * 测试 cJSON_AddStringToObject 保存的是指针还是内容
 */
#include <stdio.h>
#include <string.h>
#include "cJSON.h"

int main() {
    cJSON *json = cJSON_CreateObject();
    cJSON * string = NULL;
    char str[128] = {0};

    strcpy(str, "Hello World");
    cJSON_AddStringToObject(json, "string", str);
    memset(str, 0x00, sizeof(str));
    string = cJSON_GetObjectItem(json, "string");

    printf("str is [%s], string is [%s]\n", str, cJSON_GetStringValue(string));
    cJSON_Delete(json);
    return 0;
}

输出内容为

str is [], string is [Hello World]

可见 cjson 对象保存的是字符串内容

其实只需要看 cJSON 源代码就可以了

CJSON_PUBLIC(cJSON*) cJSON_AddStringToObject(cJSON * const object, const char * const name, const char * const string)
{
    cJSON *string_item = cJSON_CreateString(string);
    if (add_item_to_object(object, name, string_item, &global_hooks, false))
    {
        return string_item;
    }

    cJSON_Delete(string_item);
    return NULL;
}

CJSON_PUBLIC(cJSON *) cJSON_CreateString(const char *string)
{
    cJSON *item = cJSON_New_Item(&global_hooks);
    if(item)
    {
        item->type = cJSON_String;
        item->valuestring = (char*)cJSON_strdup((const unsigned char*)string, &global_hooks);
        if(!item->valuestring)
        {
            cJSON_Delete(item);
            return NULL;
        }
    }

    return item;
}

static unsigned char* cJSON_strdup(const unsigned char* string, const internal_hooks * const hooks)
{
    size_t length = 0;
    unsigned char *copy = NULL;

    if (string == NULL)
    {
        return NULL;
    }

    length = strlen((const char*)string) + sizeof("");
    copy = (unsigned char*)hooks->allocate(length);
    if (copy == NULL)
    {
        return NULL;
    }
    memcpy(copy, string, length);

    return copy;
}