c# 提示并非所有的代码路径都返回值，这段代码哪不对

static public SqlConnection GetConn()
{
try
{
string sql = null;
SqlConnForm form = new SqlConnForm();
if (form.radioButtonWin.Checked == true && SqlConnForm.dbname == "")
{
sql = @"Data Source=" + SqlConnForm.sername + ";Initial Catalog=master;Integrated Security=True";
SqlConnection conn = new SqlConnection(sql);
return conn;
}
if (form.radioButtonWin.Checked == true && SqlConnForm.dbname != "")
{
sql = @"Data Source=" + SqlConnForm.sername + ";Initial Catalog=" + form.comboBoxDbName.Text + ";Integrated Security=True";
SqlConnection conn = new SqlConnection(sql);
return conn;
}
if (form.radioButtonSQL.Checked == true && SqlConnForm.dbname == "")
{
sql = @"Data Source=" + SqlConnForm.sername + ";Initial Catalog=master;User ID=" + SqlConnForm.username + "Pwd=" + SqlConnForm.password + ";";
SqlConnection conn = new SqlConnection(sql);
return conn;
}
if (form.radioButtonSQL.Checked == true && SqlConnForm.dbname != "")
{
sql = @"Data Source=" + SqlConnForm.sername + ";Initial Catalog=" + SqlConnForm.dbname + ";User ID=" + SqlConnForm.username + "Pwd=" + SqlConnForm.password + ";";
SqlConnection conn = new SqlConnection(sql);
return conn;
}
}
catch (Exception e)
{
throw e;
}

你把return conn放到外面不就行了，还有你最好把sqlconnection弄成全局的
尝试修改成下面的代码，试一下

static public SqlConnection GetConn()
{
try
{
SqlConnection conn=null;
string sql = null;
SqlConnForm form = new SqlConnForm();
if (form.radioButtonWin.Checked == true && SqlConnForm.dbname == "")
{
sql = @"Data Source=" + SqlConnForm.sername + ";Initial Catalog=master;Integrated Security=True";
conn = new SqlConnection(sql);
}
if (form.radioButtonWin.Checked == true && SqlConnForm.dbname != "")
{
sql = @"Data Source=" + SqlConnForm.sername + ";Initial Catalog=" + form.comboBoxDbName.Text + ";Integrated Security=True";
conn = new SqlConnection(sql);
}
if (form.radioButtonSQL.Checked == true && SqlConnForm.dbname == "")
{
sql = @"Data Source=" + SqlConnForm.sername + ";Initial Catalog=master;User ID=" + SqlConnForm.username + "Pwd=" + SqlConnForm.password + ";";
conn = new SqlConnection(sql);
}
if (form.radioButtonSQL.Checked == true && SqlConnForm.dbname != "")
{
sql = @"Data Source=" + SqlConnForm.sername + ";Initial Catalog=" + SqlConnForm.dbname + ";User ID=" + SqlConnForm.username + "Pwd=" + SqlConnForm.password + ";";
conn = new SqlConnection(sql);

}
}
catch (Exception e)
{
throw e;
}
return conn;

这么和你说吧，你定义 了一个有返回值的函数，那么就一定要有返回值，现在是你只在try里返回了，如果当然try不成功（就是有错，有异常），那么就要中间断开，goto到catch，这样try里就没有返回，现在你catch里又没有返回，到函数最后也没有，那么这个函数到最后都没有返回值，如果编译器认你通过的话，如果try 出现异常，那么这个函数就不会有返值，那就是说函数没有停止，也就是说，如何在这一线程下的就这样停止，如果是主线程的话那就是程序卡在这里了，没反响， 以上都是一些啰嗦话，明白就好，像try catch 和if else 等一些判断语句，多个的还是一个的，只要函数返回值不是void 那么 每个判断都要有return .当然了如果在函数最后return 以上的都是废话