C++代码中用MySQL头文件报错解决方法讲解

Tags: c++
当在C 代码中,直接引用MySQL头文件时,可能会遇到如下错误:
In file included from /usr/include/c /4.1.0/bits/char_traits.h:46,
                 from /usr/include/c /4.1.0/string:46,
/usr/include/c /4.1.0/bits/stl_algobase.h:92:28: error: macro "swap" requires 3 arguments, but only 2 given
/usr/include/c /4.1.0/bits/stl_algobase.h:127:26: error: macro "swap" requires 3 arguments, but only 2 given

/usr/include/c /4.1.0/bits/vector.tcc:176:20: error: macro "swap" requires 3 arguments, but only 1 given
/usr/include/c /4.1.0/cctype:70: error: ::isalnum has not been declared
/usr/include/c /4.1.0/cctype:71: error: ::isalpha has not been declared
/usr/include/c /4.1.0/cctype:72: error: ::iscntrl has not been declared
/usr/include/c /4.1.0/cctype:73: error: ::isdigit has not been declared
/usr/include/c /4.1.0/cctype:74: error: ::isgraph has not been declared
/usr/include/c /4.1.0/cctype:75: error: ::islower has not been declared
/usr/include/c /4.1.0/cctype:76: error: ::isprint has not been declared
/usr/include/c /4.1.0/cctype:77: error: ::ispunct has not been declared
/usr/include/c /4.1.0/cctype:78: error: ::isspace has not been declared
/usr/include/c /4.1.0/cctype:79: error: ::isupper has not been declared
/usr/include/c /4.1.0/cctype:80: error: ::isxdigit has not been declared
/usr/include/c /4.1.0/cctype:81: error: ::tolower has not been declared
/usr/include/c /4.1.0/cctype:82: error: ::toupper has not been declared

解决办法:
尽量对MySQL进行二次包装,让调用者看不到MySQL头文件,如在CPP中包含:
#include <my_global.h>
#include <my_sys.h>
#include <mysql.h>

在头文件中只进行引用声明:
struct st_mysql;
struct st_mysql_res;

typedef long num_t;
typedef char ** MYSQL_ROW;  /** return data as array of strings */

不要在头文件直接include到MySQL的头文件,而且保证只在一个CPP文件中有对MySQL文件的include,否则你可能遇到很多莫名其妙的编译错误,如果不想到这一点,即使花一天时间也未必能找到错误原因。

补充: MySQL4.x和MySQL5.x头文件不兼容的,最好使用5.x版本
补充: 有些版本只能引用#include <mysql.h>,包含其它会报C 标准库中某文件错误。

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