Help with this C++ Program

**JDK721** · 12-11-2006

Write a program that declares a character array named alphabet and initializes the array to "ABCDEFGHIJKLMNOPQRSTUVWXYZ" In your program, include a FOR LOOP that replaces one character of the array at a time with the lowercase letters a-z. Print the character array to the screen during each iteration of the loop. Hint: Remember that a character array is an array of integer values. Use ASCII values to make the changes.

Okay, I got it to print out everything at once. How would I make it so you press a key, and it does it each time.

Because right now, its showing everything at once.

http://img292.imageshack.us/img292/9...ubitmapyz1.jpg

Code:

#include <iostream.h>
#include <iomanip.h>
#include <string.h>
#include <math.h>
 
int main()
{
char alphabet[27] = {"ABCDEFGHIJKLMNOPQRSTUVWXYZ"};

for (int i=0;i<=25;i++)
{alphabet[i] = alphabet[i] + 32;
	cout << alphabet << "\n";
}
system("pause");
return 0;
}

**manutd** · 12-11-2006

Any key? If just the enter key, use cin.get().

**JDK721** · 12-11-2006

Not the enter key, something else.. enter key is used to close the program.

**Daved** · 12-11-2006

There is no standard way to make the code wait for a keypress without the user having to hit the enter key. You could use a function specific to your platform (OS and compiler), like maybe getch(). However, it would probably be better to just use the enter key and keep your code portable.

BTW, <iostream.h> and <iomanip.h> are old and non-standard. They don't work on some modern compilers. You should be using <iostream> and <iomanip> (although you don't need <iomanip> in this program). If your instructor/book/tutorial is teaching you to use these, you should know that they are quite a bit out of date.

**manutd** · 12-11-2006

Also <cmath> not <math.h>. Plus, why have string.h?

**Daved** · 12-11-2006

>> Also <cmath> not <math.h>. Plus, why have string.h?
Both <math.h> and <string.h> are standard and will work on modern compilers, although it is of course preferable to use <cmath> and <cstring> if you need them. Of course, in this program, neither of those are necessary either.

**robatino** · 12-11-2006

Originally Posted by Daved

>> Also <cmath> not <math.h>. Plus, why have string.h?
Both <math.h> and <string.h> are standard and will work on modern compilers, although it is of course preferable to use <cmath> and <cstring> if you need them. Of course, in this program, neither of those are necessary either.

Is there any functional difference between <math.h> and <cmath>, or <string.h> and <string>, in a C++ program? And is there an ongoing trend towards doing away with all of the .h header files in C++, or is it expected that some of them will remain permanently?

**anon** · 12-11-2006

<string.h> (properly <cstring>) and <string> are completely different things.

Yes, C++ has done away with the ".h" in all standard libraries. The old C libraries (e.g "math.h") are prefixed "c" -> <cmath>
One difference is that everything is in std:: namespace, helping to avoid naming collisions (which is a good thing).

(Recently I tried to include both <windows.h> and <allegro.h> in a program, but I couldn't do it naively, because of a naming collision: both define a struct BITMAP to begin with.)

**manutd** · 12-11-2006

I said cmath as a matter of personal preference, to make it clear. Also, the OP should take note that both <math.h>/<cmath> and <string.h>/<cstring>/<string> are not needed in this program.

**robatino** · 12-11-2006

Originally Posted by anon

<string.h> (properly <cstring>) and <string> are completely different things.

Yes, C++ has done away with the ".h" in all standard libraries. The old C libraries (e.g "math.h") are prefixed "c" -> <cmath>
One difference is that everything is in std:: namespace, helping to avoid naming collisions (which is a good thing).

One program I wrote used the relatively new <inttypes.h> header, which apparently has only a C and not a C++ version yet (<cinttypes> doesn't exist). So far that's the only such case I've seen, though.

**Daved** · 12-11-2006

That's probably because <inttypes.h> is C99, and not standard in C++.

All C standard library headers that were standard in C when the C++ standard was written are also standard in C++. The C versions with the '.h' are deprecated, and the preferred alternatives for C++ programs are the versions without the '.h' and with the 'c' prefix. You can use either version in a C++ program and it will still compile on a standards-conforming compiler.

Headers added to C99 (after the C++ standard) are not standard in C++, but probably work on some compilers that also support C.

**JDK721** · 12-11-2006

We use microsoft visual C++ 5.0 at school, which I believe is 1998 so thats why you see old headers.

**Daved** · 12-11-2006

That's too bad. The Express version of the latest Visual C++ is free, and there are other free and modern options available as well. You have to work with what they require, just remember that it is outdated if you continue C++ programming beyond your current school.

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