12

In Kernighan and Ritchie (the C programming language):

'Write a program to print the value of EOF'

I wrote:

#include <stdio.h>

main(){

    int c;
    c = getchar();
    if ((c = getchar()) ==  EOF)
        putchar(c);
}

but it doesn't output anything Why?

bigTree
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    `EOF` is not a character, therefore `putchar(EOF)` can do anything. What you want is `printf("%d", EOF)`. – Konrad Borowski May 24 '14 at 11:25
  • `putchar(EOF)` is defined to mean `putchar( (unsigned char)(EOF) )` (C11 7.21.7.3) , so it can't "do anything" as such, it must output some character. Although perhaps that is a non-printable character – M.M Oct 25 '19 at 13:30

3 Answers3

19

putchar function prints a character.

But EOF is not a character and is used to indicate the End of a file. So the getchar returns a value which is distinguishable from the character sets so as to indicate there is no more input.

So printing EOF using putchar() wont print any values

printing it as integer

printf("%d",EOF);

gives result -1

Sorcrer
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9

putchar(c) means to output the character which corresponds to c (which is a number) in the character encoding in use (usually ASCII).

There is no character which is encoded as EOF (that's the whole point of EOF).

The stipulation to "print value of EOF" does not mean "print the character whose code is EOF" (since there is none). Instead they most likely mean to print the integer with the same value as EOF on your system.

M.M
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6

try this:

#include <stdio.h>

int main(){
    printf("EOF: %d\n", EOF);
}

EOF is not a printable char as you expected.

mitnk
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