1，首先导入命名空间：

using System.Runtime.InteropServices;

2，声明API函数        

[DllImport("kernel32")]        

private static extern long WritePrivateProfileString(string section, string key, string val, string filePath);

3,创建ini文件

path = Application.StartupPath + "\\ClientCfg.ini";

private void WriteIni()

{            

  WritePrivateProfileString("DataBase", "DBSource", ".", path);            

  WritePrivateProfileString("DataBase", "DBPswd", "123456", path);

  WritePrivateProfileString("DataBase", "DBAcc", "sa", path);            

  WritePrivateProfileString("DataBase", "DBName", "Train", path);

}

4，声明API函数        

[DllImport("kernel32")]        

private static extern int GetPrivateProfileString(string section, string key, string def, StringBuilder retVal, int size, string filePath);

5，读取ini文件

private void ReadIni()        

{            

StringBuilder temp = new StringBuilder();            

GetPrivateProfileString("DataBase", "DBSource", "", temp, 255, path);            

string source = temp.ToString();            

GetPrivateProfileString("DataBase", "DBPswd", "", temp, 255, path);           

string pwd = temp.ToString();            

GetPrivateProfileString("DataBase", "DBAcc", "", temp, 255, path);            

 string acc = temp.ToString();           

 GetPrivateProfileString("DataBase", "DBName", "", temp, 255, path);            

 string name = temp.ToString();

 connectionStr = "server=" + source + ";database=" + name + ";uid=" + acc + ";pwd=" + pwd + "";

}