Simple conversation question

[Holger 9]

I needed a function to change the screenresolution and frequency so I started to write code to implement to Autoit3, cause I didn't want to use an external tool like "setres.exe".

For instance one part of it is to set the display frequency through:

devMode.dmDisplayFrequency = (ulong)vParams[3].szValue();

the MSDN help shows that this parameter has to be an unsigned long value, so I do it with conversation "(ulong)".

The result ist that it doesn't work.

If I use f.i.:

devMode.dmDisplayFrequency = 75;

then the screenfrequency will change.

Hmmm....I don't know...I've looked into my c++book but can't find anything about it...

Has anyone of you an idea? maybe with "strtoul"?

Thanks for your help and regards

Edited June 11, 2004 by Holger

[Holger 9]

@Larry: thanks so much

So simple that I didn't see that

[Valik 468]

One good example of why C++ casts (Although slightly cumbersome) are much better. Attempting to compile your code with the C-style cast, I get a pointer truncation Warning. Attempting to compile by using a C++ cast, I get an Error.

devMode.dmDisplayFrequency = static_cast<ulong>(vParams[3].szValue());

error C2440: 'static_cast' : cannot convert from 'const char *' to 'unsigned long'

        This conversion requires a reinterpret_cast, a C-style cast or function-style cast

Just a little food for thought, I use C-style casts in too many places also, hard habit to break.

[Nutster 2]

szValue() returns a string (char *) and nValue() returns a number (double). If you want numeric values, use nValue().

[Holger 9]

@all: thanks for your answer's, it works now