c# - What causes the error "Not all code paths return a value"?

Question

public string Valid(OleDbDataReader myreader, int stval)
{
    object val = myreader[stval];

    if (val != DBNull.Value)
    {
        return val.ToString() ;
    }
    else
    {
        Convert.ToString(0);
    }
}

There is a Error " not all code paths return a value" please Help

Answer 1

You need to read about basic of C functions.

As function returning string value it must return a value in all cases. This includes the else part also.

The reason is if there else part is executed than you need to return string value, but there is no return there:

public string Valid(OleDbDataReader myreader, int stval)
    {
        object val = myreader[stval];
        if (val != DBNull.Value)
        {
            return val.ToString() ;
        }
        else
        {
           return Convert.ToString(0); //forgot to write return over her
        }
    }