Funny results with printf() vs putchar(). !!

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March 11th, 2013, 01:24 AM

saurabhmangal

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Funny results with printf() vs putchar(). !!

Dear experts,

I am working on a beginner level program and got stuck:

Code:

#include<stdio.h>
#include<conio.h>
void main()
{
	char a;
	int i;
	for (i = 0; i <3; i++)
	{
		a = getch();

                // any two out the four below in ANY ORDER
		
                //printf("%c",a);
		   printf("%c",a);
		   putchar(a);
		//putchar(a);
	}
	getch();
}

I see that no matter what combination of printf() and putchar() (total calls 2) I give, I only get the character printed ONCE (instead of 2 as I expected). Giving only one of them does not print the character at all.. Strange. Please throw some light on it.

sample input/output:
aabbcc

Thanks,
Saurabh.

March 11th, 2013, 02:42 AM

salem

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> #include<conio.h>
This header file is obsolete, stop using it

> void main()
The standard requires that main returns an int.
My guess is you're using TurboC, which basically became obsolete around 1990.

Yes I'm well aware that many colleges have institutionalised obsolescence, but students need to know they're being ripped off all the same. It might not be costing you financially, but you are being screwed by being fed ancient crap.

> a = getch();
Use the portable function.
a = getchar();

After your printf and/or putchar, follow with
fflush(stdout);

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March 11th, 2013, 10:41 AM

b49P23TIvg

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Follow Salem's advice. gcc is a modern compiler alternative.

Based on what you do have:
"getch function prompts the user to press a character and that character is not printed on screen"

printf and putchar are showing the character. It is getch that you're misunderstanding.

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March 12th, 2013, 12:43 AM

saurabhmangal

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Thanks

Thanks to the people who replied. I want to know this:

1) Can I get gcc or any other modern compiler for windows (I am not sure how to initiate debugging in Visual studio)
2) what is the substitute of conio.h if it is obsolete?
3) What is meant by portable function (getchar vs getch)?

thanks,
Saurabh.

March 12th, 2013, 01:13 AM

salem

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1) Can I get gcc or any other modern compiler for windows (I am not sure how to initiate debugging in Visual studio)
Modern compilers to try.
http://www.microsoft.com/express/Downloads/
http://www.smorgasbordet.com/pellesc/
http://www.codeblocks.org/
http://sourceforge.net/projects/orwelldevcpp/
The last two are IDEs which come pre-packaged with the MinGW port of the GCC compiler.

2) what is the substitute of conio.h if it is obsolete?
Well it depends which OS/Compiler you're using.
A reasonably portable library is pdcurses, (click) (click) which will allow you to do more things on a console than conio.h ever could, and allow you to run the same code in different environments if you chose to later on.

3) What is meant by portable function (getchar vs getch)?
It means EVERY compiler provides getchar() - it's a standard function.
Even if two systems have getch(), there is no guarantee that they do the same thing.