在其基础上，添加了cJSON_Direct.c，实现了C语言中结构体与json格式字符串相互转化的功能-Json parsing code is written by a foreigner. On its basis, add cJSON_Direct.c to C language structure and JSON-formatted string into each other

编译原理：数学公式转化html语言格式的词法分析器(Lexical analyzer for converting mathematical formulas into HTML format)