Something odd with putchar()...

**Hakins90** · 12-26-2007

I am writing a simple program with using getchar() and putchar() which outputs the next letter up in the alphabet from the input.

Here is my code :

Code:

#include <stdio.h>

int main(void) {
	char c;
	printf("Enter letters: ");
	while((c = getchar()) != '0') {
		putchar(++c);
	}
}

If i input the letters abcde pressing enter in between each the output is -

Enter letters: a
b♂b
c♂c
d♂d
e♂e
f♂f
g♂g
h♂

First of all, why are newline characters being outputted? Can this be stopped?
Secondly, why does the '\n' character get incremented to '\v' aswell as the alphabet character?

Thankyou

**dwks** · 12-26-2007

Well, your code increments every character it comes across before printing it. Since getchar() returns every character you type (except for backspace etc), including <enter>, well, that's what you get. An incremented '\n'.

The newline character is "printed" because you typed it. There's no standard way to avoid this happening.

But if you're willing to be non-standard, you can use things like getche() (from <conio.h>, for Dev-C++) to get every character you could think of, including backspace and '\n'. I think it still echos the newline, though.

**MacGyver** · 12-26-2007

If you're willing to go non-standard, learn the *nix or Windows methods for dealing with input. Please don't use conio.h. lol...

**dwks** · 12-26-2007

It should also be noted that typing a '\0' is not usually how you end input. You can type a '\0', usually; CTRL-SHIFT-2 on DOS systems. But EOF is the standard "character". You can type it with CTRL-Z, plus that's what happens automatically when you redirect a file for input to your program.

EOF can only be stored in an int, not a char. So you should probably use an int in your code.

**whiteflags** · 12-26-2007

An idea. I don't think I'm missing anything.

Code:

#include <stdio.h>
#include <ctype.h>

int main( void )
{
    int ch;

    while( ( ch = getchar() ) != EOF ) {
        if( isalpha( ch ) )
            putchar( ++ch );
        else
            putchar( ch );
    }
    return 0;
}

this is the 1st test!!
uijt jt uif 1tu uftu!!
does it work??
epft ju xpsl??
yes, goodbye
zft, hppeczf
^Z

**MacGyver** · 12-26-2007

Time to (ab)use the ternary operator.

Code:

putchar( isalpha(ch) ? ++ch : ch );

**Salem** · 12-27-2007

Or, since nothing actually depends on the computed result,

Code:

putchar( isalpha(ch) ? ch+1 : ch );

**Hakins90** · 12-27-2007

Thankyou all for your help

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