1、在头部引用

[DllImport("kernel32")] 
private static extern long WritePrivateProfileString(string section, 
    string key,string val,string filePath); 
 
[DllImport("kernel32")] 
private static extern int GetPrivateProfileString(string section, 
    string key,string def, StringBuilder retVal, 
    int size,string filePath); 

2、写入.ini

WritePrivateProfileString("Setup","UserName",userno.Text,Application.StartupPath+"\\mcs.ini"); 

3、读取.ini

StringBuilder temp = new StringBuilder(255); 
int i = GetPrivateProfileString("Setup","UserName","",temp,255, Application.StartupPath+"\\mcs.ini"); 
userno.Text = temp.ToString();