Thread: Why the program prints line twice?

Hi all!

I cannot figure out why the output prints the printf line twice.. in this program.. thanks..

here is the code with the output:

Code:

#include<stdio.h>
main()
{
char ch;
while (ch!='0')
	{
	printf("enter a char other than 0\n");
	ch=getchar();
	}
}

enter a char other than 0
d
enter a char other than 0
enter a char other than 0

well, it prints "enter a char other than 0" twice...

Originally Posted by red463

Hi all!

I cannot figure out why the output prints the printf line twice.. in this program.. thanks..

here is the code with the output:

Code:

#include<stdio.h>
main()
{
char ch;
while (ch!='0')
	{
	printf("enter a char other than 0\n");
	ch=getchar();
	}
}

enter a char other than 0
d
enter a char other than 0
enter a char other than 0

Yes, but you are also probably pressing another button after 'd'.

This is where I believe quzah is trying to lead you.

Also, on another note, initialize your variables before use. -- although this is not the reason you are getting that behavior.

what is the solution to this problem?

ok teacher, what is the right way to deal with this then?

Originally Posted by red463

ok teacher, what is the right way to deal with this then?

The answer is either "recognize that this is the right answer" or "also check if the read character is enter-key". (EDIT TO ADD: For instance, think about what happens when they type "flibbertigibbet" at the prompt.)

Originally Posted by tabstop

The answer is either "recognize that this is the right answer" or "also check if the read character is enter-key". (EDIT TO ADD: For instance, think about what happens when they type "flibbertigibbet" at the prompt.)

when you do that, it would print the command n+1 times (n=number of chars in flibbertigibbet).
I would please like to know how to deal with this, I am very new to programming, and cryptic answers aren't helping me here...

Originally Posted by red463

when you do that, it would print the command n+1 times (n=number of chars in flibbertigibbet).
I would please like to know how to deal with this, I am very new to programming, and cryptic answers aren't helping me here...

It really depends on what the specs of the program are. If the specs are something like "print a prompt and read a character; if the character is not '0', then repeat" then we will say it for the fourth time in this thread: there is no error in your code and therefore there is nothing to fix. If the specs are something other than that, then you need to tell us what they are.

allright, my bad, the spec follows-

write a program, which allows users to enter characters until the input is '0'.

well, thanks for all the help guys...