JSON to cJSON Class

Tool Introduction

"JSON to cJSON Class" is an efficient online tool designed to help C/C++ developers automatically convert complex JSON data structures into C language struct definitions or cJSON object construction code directly usable by the cJSON library. It greatly simplifies the tedious process of manually writing JSON parsing code, improving development efficiency, especially suitable for embedded systems or high-performance application development that frequently need to process JSON data.

How to Use

1. Paste the JSON string you need to convert into the input box.
2. According to your needs, select the output type: whether to generate C language struct definitions or cJSON object construction code. Some tools may provide custom options, such as struct namespace, field prefix, etc. Please configure them according to the interface prompts.
3. Click the "Convert" or "Generate Code" button, and the tool will output the corresponding C language code in real-time.

Input Parameter Format and Requirements

Input parameters must be strings that comply with standard JSON specifications. Whether it's simple key-value pairs or complex nested objects and arrays, the tool can parse them.

Output Result Format

The output result is C language code in plain text format. When choosing to generate structs, the output is `typedef struct {...}` definitions; when choosing to generate cJSON object construction code, the output is a series of `cJSON_Create...` and `cJSON_AddItem...` function calls.

Usage Example

Below is an example of converting JSON data into C language struct definitions.

• Example Input Data:

  {
    "bookId": "B001",
    "title": "C++ Primer Plus",
    "author": "Stephen Prata",
    "price": 69.90,
    "isAvailable": true,
    "tags": ["Programming", "C++", "Beginner"],
    "details": {
      "publisher": "Addison-Wesley Professional",
      "pages": 1344
    }
  }

• Expected Output Result (C Struct Definition):

  typedef struct {
      char *publisher;
      int pages;
  } BookDetails;
  
  typedef struct {
      char *bookId;
      char *title;
      char *author;
      double price;
      bool isAvailable;
      char **tags;  // Array, requires manual memory and length handling
      int tags_count;
      BookDetails details;
  } BookInfo;

• Specific Operation Demo: Users only need to copy the above JSON data, paste it into the tool's input box, select the "Generate C Struct" option, and then click the "Convert" button to immediately see the C struct code as shown above.

Frequently Asked Questions

• Q: What input formats are supported? A: This tool supports standard JSON string format input, including objects, arrays, strings, numbers, booleans, and null.
• Q: What is the format of the output result? A: The main output is C language struct definition code or C code that uses the cJSON library to create cJSON objects, which is convenient for integration into your C/C++ projects.
• Q: Can it handle complex nested JSON structures? A: Yes, this tool can recognize and process multi-level nested JSON objects and arrays, and generate corresponding nested structs or cJSON object construction code.
• Q: Are the generated struct field names and types configurable? A: In most cases, the tool automatically generates field names based on JSON keys and infers C types based on JSON value types. Advanced versions may provide configuration options, allowing users to customize naming rules and type mappings.

Notes

• Input Data Format Requirements: Please ensure that the input JSON data format is completely correct and valid. Any format errors may lead to conversion failure or incorrect code generation. It is recommended to use an online JSON validation tool to check beforehand.
• Memory Management: If you choose to generate cJSON object construction code, please pay attention to the cJSON library's memory management. After using a cJSON object, you should promptly call the `cJSON_Delete()` function to free memory and avoid memory leaks.
• Array Handling: For JSON array types, the generated C struct will usually contain a pointer to the element type and an integer member representing the number of elements (e.g., `char **tags; int tags_count;`), you need to perform memory allocation and iteration processing according to the actual situation.
• Data Type Mapping: The tool will try its best to map JSON data types to common C language types (such as strings to `char*`, integers to `int`, floating-point numbers to `double`, booleans to `bool`). For some special or custom types, users may need to manually adjust the generated code.

Introduction to JSON and cJSON

JSON (JavaScript Object Notation) is a lightweight data-interchange format. It is easy for humans to read and write, and also easy for machines to parse and generate. JSON is based on a subset of the JavaScript programming language, but it is a language-independent data format, widely used in web services, API interfaces, and data transmission between various applications.

cJSON is an ultra-lightweight C language JSON parser and generator library. Its design goal is simplicity, efficiency, and low resource consumption, making it very suitable for processing JSON data in embedded systems, IoT devices, and C/C++ projects with strict performance and memory requirements. cJSON provides a series of simple and intuitive API functions, allowing developers to easily create, parse, and manipulate JSON objects.