Thread: Displaying a variable in a msg box.

I think the question they meant to ask was "Spidey, how much Windows programming have you done?" (since I imagine there are C/C++ programmers who have gone their whole lives without using MessageBox).

Hehe. Quite true. Nice catch. But since MessageBox() takes two LPCTSTRs one would have to know how to pass in C style strings in order to get it to work for them. So in this instance I can see how some might question a person's knowledge of C/C++ if they did not know how to get MessageBox() to display what they wanted.

Yes but that does not give you the number since you passed in a string literal.

Yes, thats what I meant.

I think the question they meant to ask was "Spidey, how much Windows programming have you done?" (since I imagine there are C/C++ programmers who have gone their whole lives without using MessageBox).

That would be little to none.

Well, I just saw the missing comma which looked suspicious so I assumed it would be wrong anyway.

Thats because your never storing the value of x in the text. You need a format specifier, like this

Code:

 sprintf(text,"The num is : %d",x);

This is a C++ forum. Why don't you use C++?

Code:

#include <string>
#include <sstream>

/* ...*/

	std::string msgtxt = "The num is : ";
	std::ostringstream ostr;
	int x = 13;

	ostr << msgtxt << x; // concatenation happens here

        //c_str() because ostringstream.str() returns a std::string
        MessageBox(NULL, ostr.str().c_str(), "Msg", MB_OK);

Well my first problem is over but now I have another one:

Code:

		sprintf(text1,"x is : % d", x);
		sprintf(text2,"Y is : % d", y);
		strcat(main, text1);
		strcat(main, "\n\n");
		strcat(main, text2);
		MessageBox(NULL, main , "msg",MB_OK);

When i do this and test it the msg box shows this

D[]ox is : 4

y is: 5

why does is show the 3 charachters at the beginning ?

When i do this it works perfectly but only shows one string :

Code:

		sprintf(text1,"x is : % d", x);
		sprintf(text2,"Y is : % d", y);
		strcat(main, text1);
		strcat(main, "\n\n");
		strcat(main, text2);
		MessageBox(NULL, text1 , "msg",MB_OK);

Main doesn't contain any thing i checked and rechecked

P.s.The three charachters are special charchters described below:


THE FIRST IS A Dwith a line through it

The second is a square(not 2 brackets)

and the third is the letter o


See signature for picture

Originally Posted by Yarin

You may not have put anything in main, but when your program allocated the memory for main during run-time, the contents of main were left undefined - basically, there's never any telling what your allocated memory's content will start out as! That's why you're suppose to zero out main first, replace the first strcat() with strcpy(), or, just use std::string as we continue to advice you to do instead.

Thanks

And why do you still insist on using the C approach!?!

And why do you still insist on using the C approach!?!

Either approach is valid whether it be via stringstream or via sprintf. Since this is a C++ forum then naturally we would recommend the stringstream approach. However that does not make it more or less right in a purely technical sense. Both will accomplish the goal and both will get the job done. To me there is no benefit in using C++ just to be more C++-ey and in this instance it makes no difference either way. When I use a C++ approach to solve a problem it is for a very distinct reason and to serve a specific purpose. It is not merely to please the C++ gods whoever they may be or to look myself in the mirror in the morning and pride myself on being a C++ programmer.