Adding strings together using strcat

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Phosphoer

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Joined: 8th Dec 2007

Location: Seattle

Posted: 17th Oct 2008 23:42

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Hey guys, I'm trying to add several strings together before loading a file with the result as the filename. I searched the forums and learned that a way to do it is by using strcat.

I used this code:

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char* filebase = "Levels/Level";
char* LevelNumber;
LevelNumber = "1.txt";
strcat(filebase,LevelNumber);
ifstream myfile (filebase);

Note that for now LevelNumber is constant because I'm just testing the function, in the future I'll replace it with dbStr(CurrentLevel) or something.

Anyway, when I run this code, the program crashes. It just freezes completely, I have to force quit visual c++. Any ideas what I'm doing wrong?

Thanks

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prasoc

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Posted: 18th Oct 2008 00:07

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Are you sure Level1.txt exists? maybe it is Level01.txt?

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Phosphoer

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Location: Seattle

Posted: 18th Oct 2008 00:21 Edited at: 18th Oct 2008 00:36

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Update, It no longer crashes, but the text output is all distorted.

It's supposed to output Level1.txt, but instead I get Level1.t0Y, where 0 is a white square, and Y is in a weird font.

My new code:

+ Code Snippet

	char* result;
	char destination [ ] = "Level";
	char addedStuff [ ] = "1.txt";
	result = strcat(destination, addedStuff);
	ifstream myfile (result);
	dbText(10,10,result);

Edited:
Nevermind! It works now, I realized that I wasn't specifying the size of the chars, I changed the size to 256 and it works now ^^.

Second edit:
So now that I have that, I want to replace the "1.txt" with a variable value.

I have an integer value for CurrentLevel that I want to replace the 1 with, but I want to keep the ".txt" constant.
How would I accomplish the DBP equivalent of "Level" + Str$(1) + ".txt"?

Thanks

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Lilith

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Joined: 12th Feb 2008

Location: Dallas, TX

Posted: 18th Oct 2008 02:23

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When you declare

char destination [] = "Level";

you're reserving only enough space to contain the characters in the string and the terminating zero. When you concatenate more text to it, it's being stored in unknown territory and probably is banging into other stored data.

Try

char destination [128] = "Level";

That will reserve enough space for most added text.

Lilith, Night Butterfly
I'm not a programmer but I play one in the office

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Phosphoer

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Posted: 18th Oct 2008 23:48

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Aha ^^, that worked. Thanks much!