本文目录一览：
c语言中undefined reference to ""怎么解决
大部分原因是链接时缺失了相关目标文件
首先编写如下代码
// test.h
#ifndef __TEST_H__
#define __TEST_H__
void test();
#endif
// test.c
#include string.h
#include stdio.h
void test()
{
printf("just test itn");
}
// main.c
#include "test.h"
int main(int argc, char **argv)
{
test();
return 0;
}
然后输入以下命令,你会得到两个.o文件
$ gcc -c test.c
$ gcc –c main.c
编译时报错了，这是最典型的undefined reference错误，因为在链接时发现找不到某个函数的实现文件。编写如下命令即可。
$ gcc -o main main.o test.o
c++builder 6.0 里面的json类在哪
BCB6 不带json的要2010版本的才有，不过建议自己写一个 用起来更方便
/*
Copyright (c) 2009 Dave Gamble
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
*/
#ifndef cJSON__h
#define cJSON__h
#ifdef __cplusplus
extern "C"
{
#endif
/* cJSON Types: */
#define cJSON_False 0
#define cJSON_True 1
#define cJSON_NULL 2
#define cJSON_Number 3
#define cJSON_String 4
#define cJSON_Array 5
#define cJSON_Object 6
#define cJSON_IsReference 256
/* The cJSON structure: */
typedef struct cJSON {
struct cJSON *next,*prev; /* next/prev allow you to walk array/object chains. Alternatively, use GetArraySize/GetArrayItem/GetObjectItem */
struct cJSON *child; /* An array or object item will have a child pointer pointing to a chain of the items in the array/object. */
int type; /* The type of the item, as above. */
char *valuestring; /* The item's string, if type==cJSON_String */
int valueint; /* The item's number, if type==cJSON_Number */
double valuedouble; /* The item's number, if type==cJSON_Number */
char *string; /* The item's name string, if this item is the child of, or is in the list of subitems of an object. */
} cJSON;
typedef struct cJSON_Hooks {
void *(*malloc_fn)(size_t sz);
void (*free_fn)(void *ptr);
} cJSON_Hooks;
/* Supply malloc, realloc and free functions to cJSON */
extern void cJSON_InitHooks(cJSON_Hooks* hooks);
/* Supply a block of JSON, and this returns a cJSON object you can interrogate. Call cJSON_Delete when finished. */
extern cJSON *cJSON_Parse(const char *value);
/* Render a cJSON entity to text for transfer/storage. Free the char* when finished. */
extern char *cJSON_Print(cJSON *item);
/* Render a cJSON entity to text for transfer/storage without any formatting. Free the char* when finished. */
extern char *cJSON_PrintUnformatted(cJSON *item);
/* Delete a cJSON entity and all subentities. */
extern void cJSON_Delete(cJSON *c);
/* Returns the number of items in an array (or object). */
extern int cJSON_GetArraySize(cJSON *array);
/* Retrieve item number "item" from array "array". Returns NULL if unsuccessful. */
extern cJSON *cJSON_GetArrayItem(cJSON *array,int item);
/* Get item "string" from object. Case insensitive. */
extern cJSON *cJSON_GetObjectItem(cJSON *object,const char *string);
/* For analysing failed parses. This returns a pointer to the parse error. You'll probably need to look a few chars back to make sense of it. Defined when cJSON_Parse() returns 0. 0 when cJSON_Parse() succeeds. */
extern const char *cJSON_GetErrorPtr();
/* These calls create a cJSON item of the appropriate type. */
extern cJSON *cJSON_CreateNull();
extern cJSON *cJSON_CreateTrue();
extern cJSON *cJSON_CreateFalse();
extern cJSON *cJSON_CreateBool(int b);
extern cJSON *cJSON_CreateNumber(double num);
extern cJSON *cJSON_CreateString(const char *string);
extern cJSON *cJSON_CreateArray();
extern cJSON *cJSON_CreateObject();
/* These utilities create an Array of count items. */
extern cJSON *cJSON_CreateIntArray(int *numbers,int count);
extern cJSON *cJSON_CreateFloatArray(float *numbers,int count);
extern cJSON *cJSON_CreateDoubleArray(double *numbers,int count);
extern cJSON *cJSON_CreateStringArray(const char **strings,int count);
/* Append item to the specified array/object. */
extern void cJSON_AddItemToArray(cJSON *array, cJSON *item);
extern void cJSON_AddItemToObject(cJSON *object,const char *string,cJSON *item);
/* Append reference to item to the specified array/object. Use this when you want to add an existing cJSON to a new cJSON, but don't want to corrupt your existing cJSON. */
extern void cJSON_AddItemReferenceToArray(cJSON *array, cJSON *item);
extern void cJSON_AddItemReferenceToObject(cJSON *object,const char *string,cJSON *item);
/* Remove/Detatch items from Arrays/Objects. */
extern cJSON *cJSON_DetachItemFromArray(cJSON *array,int which);
extern void cJSON_DeleteItemFromArray(cJSON *array,int which);
extern cJSON *cJSON_DetachItemFromObject(cJSON *object,const char *string);
extern void cJSON_DeleteItemFromObject(cJSON *object,const char *string);
/* Update array items. */
extern void cJSON_ReplaceItemInArray(cJSON *array,int which,cJSON *newitem);
extern void cJSON_ReplaceItemInObject(cJSON *object,const char *string,cJSON *newitem);
#define cJSON_AddNullToObject(object,name) cJSON_AddItemToObject(object, name, cJSON_CreateNull())
#define cJSON_AddTrueToObject(object,name) cJSON_AddItemToObject(object, name, cJSON_CreateTrue())
#define cJSON_AddFalseToObject(object,name) cJSON_AddItemToObject(object, name, cJSON_CreateFalse())
#define cJSON_AddNumberToObject(object,name,n) cJSON_AddItemToObject(object, name, cJSON_CreateNumber(n))
#define cJSON_AddStringToObject(object,name,s) cJSON_AddItemToObject(object, name, cJSON_CreateString(s))
#ifdef __cplusplus
}
#endif
#endif
c语言的cjson怎样处理转义
的JSON数据格式有问题，所有Name键的值后面少了单引号， 应该修改形如这样格式的字符
如何修改 cjson
这是fastjson的例子
JSONObject json = JSON.parseObject("{val: 123}");
System.out.println("======before=====");
System.out.println("size: " + json.size());
System.out.println("val: " + json.get("val"));
json.put("val", 234); // 直接put相同的key
System.out.println("======after======");
System.out.println("size: " + json.size());
System.out.println("val: " + json.get("val"));
结果
======before=====
size: 1
val: 123
======after======
size: 1
val: 234