while ((c = getchar()) != EOF), AND cntrl z

This is a discussion on while ((c = getchar()) != EOF), AND cntrl z within the C Programming forums, part of the General Programming Boards category; I want to use getchar() to process a string. Here's a simplified version. I've used this code before to stop ...

  1. #1
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    while ((c = getchar()) != EOF), AND cntrl z

    I want to use getchar() to process a string. Here's a simplified version. I've used this code before to stop entering characters when the user enters the new-line character with no problem:
    Code:
    while ((c = getchar()) != '\n'){    
    	printf("%c", c);
    {
    However, I prefer to read in the newline characters as part of the string. That brings to my question; I don't really understand EOF and "cntrl z". Is entering "cntrl z" in the keyboard suposed to be the same as EOF? The problem is that when the user enters "cntrl z" to simulate (or so i think) EOF, it completely exits the program. Maybe my misunderstanding is simply 'How do i simulate EOF form a windows keyboard?

    This code does not do what I want because the end of the code never gets executed; it just completely exits the program when I press cntrl z. Again, is cntrl z the correct way to simulate EOF on a windows keyboard.
    Code:
    while ((c = getchar()) != EOF){
    	printf("%c", c);
    {
    ...rest of code never gets executed
    Last edited by Roger; 10-21-2009 at 04:21 PM.

  2. #2
    ATH0 quzah's Avatar
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    It's OS dependent. It will either be CTRL Z or CTRL D. Don't listen to people who say it's CTRL C, they're dumb.


    Quzah.
    Hope is the first step on the road to disappointment.

  3. #3
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    for unix its ctrl+z i think

    and windows ctrl+D, not totally sure

  4. #4
    Captain Crash brewbuck's Avatar
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    Quote Originally Posted by Obelisk View Post
    for unix its ctrl+z i think

    and windows ctrl+D, not totally sure
    That's backwards. Ctrl-Z on windows, Ctrl-D on UNIX
    Code:
    //try
    //{
    	if (a) do { f( b); } while(1);
    	else   do { f(!b); } while(1);
    //}

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    Cntrl D seems to be better but still not working.

    I should have said I'm remotely using a linux system with a Windows PC. Cntrl d seems to be working. Here's the code:
    Code:
    #include <stdio.h>
    
    int main(){
    	char c;
    	while ((c = getchar()) != EOF){
    		printf("%c", c);
    	}
    	printf("test");
    }
    This is exactly what happens:
    1) user enters characters
    2) user presses cntrl-d
    3) prints characters
    4) user presses cntrl-d a second time
    5) prints "test"

    The user should not have to press cntrl-d a second time to execute rest of program. What am I doing wrong?

    Thanks for the help.

  6. #6
    and the Hat of Guessing tabstop's Avatar
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    IIRC, both on linux and on windows, Ctrl-<as appropriate> is only EOF if it is the start of the line.

  7. #7
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    Quote Originally Posted by brewbuck View Post
    That's backwards. Ctrl-Z on windows, Ctrl-D on UNIX
    oh yea, my apologies just checked it out. thnx for the correction

  8. #8
    cas
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    Incidentally, c should be an int, not a char. Even though the function is called getchar(), it returns an int so that it's able to represent all character values plus EOF. If c is a char, you'll probably see behavior where either a normal character can trigger EOF, or that EOF is never caught.

  9. #9
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    Quote Originally Posted by Roger View Post
    I should have said I'm remotely using a linux system with a Windows PC. Cntrl d seems to be working. Here's the code:
    Code:
    #include <stdio.h>
    
    int main(){
    	char c;
    	while ((c = getchar()) != EOF){
    		printf("%c", c);
    	}
    	printf("test");
    }
    This is exactly what happens:
    1) user enters characters
    2) user presses cntrl-d
    3) prints characters
    4) user presses cntrl-d a second time
    5) prints "test"

    The user should not have to press cntrl-d a second time to execute rest of program. What am I doing wrong?

    Thanks for the help.
    as cas said c should be int

    where c contains the ascII value of the variable

    Then if you want to get the char again

    use Putchar(c)

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