Golang in the CGO use method, call the MySQL library as a case

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Golang about CGO documents relatively few, so I definitely write a simple case, here with MySQL to do case, one is to call C inside the function, one is completely with the Golang to point with the Mysql library function. My environment is the MAC, if the test, please LDFLAGS correspond to their own environment to write.

Note the place

Golang's CGO reference must be a separate line, meaning the following must be written

import "C"

There is no c.null type in CGO, so you have to use nil

Package main/* #include <stdio.h> #include <stdlib.h> #include <stdarg.h> #include "/usr/local/mysql/ Include/mysql.h "MySQL *mysql,*res; Mysql_res *results;    Mysql_field *field;        struct person {char *name;        int age;        int height;    int weight; }; #cgo Darwin ldflags:-i/usr/local/mysql/include-l/usr/local/mysql/lib-lmysqlclientvoid get_mysql_query () {MYSQL_    Row row;   MySQL = Mysql_init (NULL);   Mysql_options (MySQL, Mysql_read_default_group, "libmysqld_client");   res = mysql_real_connect (mysql, "127.0.0.1", "root", "dgj99349", "MyBlog", 0,null,0);        if (mysql_query (res, "SELECT * from Wp_users")) {fprintf (stderr, "Query failed (%s)/n", Mysql_error (res));   Exit (1); } if (! (        Results=mysql_store_result (res))) {fprintf (stderr, "couldn ' t get result from%s/n", Mysql_error (res));    Exit (1);   } int number = Mysql_num_fields (results); while (row = mysql_fetch_row (results))) {for (int i = 0; i < number; i++) {if (field = Mysql_fetch_field (results))!=null) {printf ("Field_name is:%s, Field_val         UE is:%s \ n ", Field->name,row[i]);   }}} mysql_free_result (results);   Mysql_close (MySQL);   Mysql_server_end (); return;} */import "C" import "FMT" import "unsafe" const (maxSize = 1 <<) func main () {c.puts (c.cstring ("C MYS QL function Query ... ")) C.get_mysql_query () c.puts (c.cstring (" C MySQL use library function query ...    ")/////Use C's function library to initialize mysql * mysql: = c.mysql_init (nil); Use the library to connect MySQL * c.mysql_real_connect (MySQL, c.cstring ("127.0.0.1"), c.cstring ("root"), c.cstring ("dgj99349"), C.    CString ("MyBlog"), 0,nil,0); query function int c.mysql_query (mysql,c.cstring ("SELECT * from Wp_users"))//Query result mysql_res * Results: = C.mysql_sto    Re_result (MySQL)//query number of fields unsigned int numbers: = C.mysql_num_fields (results); Query result char **mysql_row ROW: = C.mysql_fetch_row (results)//query field result mysql_field * Field: = C.MYsql_fetch_field (Results)//The length of the contents of each field unsigned long sql_lengths: = C.mysql_fetch_lengths (results) Lengths: = ( *[maxsize]uint64) (unsafe. Pointer (sql_lengths)) Cfields: = (*[maxsize]c.mysql_field) (unsafe. Pointer (field)) Rowptr: = (*[maxsize]*[maxsize]byte) (unsafe. Pointer (Row)) for I: = 0; i < int (number); i++ {length: = Cfields[i].name_length fname: = (*[maxsize]byte) (unsafe. Pointer (Cfields[i].name)) [: Length] fmt. Print ("Field_name is:", String (fname)) fmt.    Println (", Field_value is:", String (Rowptr[i][:lengths[i]))}//Release result C.mysql_free_result (results);    Turn off MySQL c.mysql_close (MySQL);   C.mysql_server_end (); }

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