c 自動拼接json類是一種非常有用的工具，它可以幫助我們自動拼接json格式的數據，從而方便我們進行數據傳遞和處理。

#include#include#include#define BUF_SIZE 1024
typedef struct JSON_ITEM {
char *key;
char *value;
struct JSON_ITEM *next;
} json_item;
typedef struct JSON {
json_item *head;
json_item *tail;
} json;
json *new_json() {
json *j = (json*)malloc(sizeof(json));
j->head = NULL;
j->tail = NULL;
return j;
}
void json_free(json *j) {
json_item *cur = j->head;
while (cur != NULL) {
free(cur->key);
free(cur->value);
json_item *next = cur->next;
free(cur);
cur = next;
}
free(j);
}
void json_add_item(json *j, const char *key, const char *value) {
json_item *item = (json_item*)malloc(sizeof(json_item));
item->key = strdup(key);
item->value = strdup(value);
item->next = NULL;
if (j->head == NULL) {
j->head = item;
j->tail = item;
} else {
j->tail->next = item;
j->tail = item;
}
}
void json_print(json *j) {
printf("{");
json_item *cur = j->head;
while (cur != NULL) {
printf("\"%s\":\"%s\"", cur->key, cur->value);
cur = cur->next;
if (cur != NULL) {
printf(",");
}
}
printf("}\n");
}
char *json_to_string(json *j) {
size_t len = 0;
json_item *cur = j->head;
while (cur != NULL) {
len += strlen(cur->key) + strlen(cur->value) + 5;
cur = cur->next;
}
char *buf = (char*)malloc(len + 1);
if (buf == NULL) {
return NULL;
}
char *p = buf;
*p++ = '{';
cur = j->head;
while (cur != NULL) {
p += sprintf(p, "\"%s\":\"%s\"", cur->key, cur->value);
cur = cur->next;
if (cur != NULL) {
*p++ = ',';
}
}
*p++ = '}';
*p = '\0';
return buf;
}
int main() {
json *j = new_json();
json_add_item(j, "name", "Alice");
json_add_item(j, "age", "18");
json_add_item(j, "gender", "female");
json_print(j);
char *str = json_to_string(j);
printf("%s\n", str);
free(str);
json_free(j);
return 0;
}

代碼中使用了兩個結構體：json和json_item，分別用來表示整個json和其中的每個條目。使用方式很簡單，只需要調用json_add_item函數來添加條目，然后調用json_to_string函數將json轉化為字符串即可。