Error Messages Appear Even After Turning Off

Symptom

After the application initializes CodeBase, the application attempts to suppress error messages by setting CODE4.errOff to true. Even so, some CodeBase functions generate an error message.

Explanation

When CodeBase generates an error and CodeBase does not have access to the CODE4 object, CodeBase always generates an error message.

This most commonly happens when an application does not perform sufficient error checking. Consider the following sample code.

   CODE4 cb;
   DATA4 *data;
   FIELD4 *field;
   code4init(&cb);
   cb.errOff = 1;
   data = d4open(&cb, "this_does_not_exist.dbf");
   field = d4field(data, "last_name");

In this sample code, d4open fails and CodeBase will not display an error message. This is because d4open is passed the CODE4 pointer and can see the errOff flag.

However, because this sample code does not check whether d4open was successful, the code is allowed to call d4field, passing the null pointer that was returned by d4open. When d4field receives this invalid parameter, it must generate an error, and because this pointer is null, d4field has no way to see the CODE4 object and the errOff flag. Therefore, d4field displays an error message.

Solution

Do not allow an invalid parameter to be passed to a function. Proper error checking would look like the following sample code.

   CODE4 cb;
   DATA4 *data;
   FIELD4 *field;
   code4init(&cb);
   cb.errOff = 1;
   data = d4open(&cb, "this_does_not_exist.dbf");
   if (data)
   {
      field = d4field(data, "last_name");