CODEWITHSUNDEEP
cscanf
Harold
Harold

Reputation: 3

C : How to stop the loop when getting the end of input from keyboard or file while using scanf one char at a time

void main(void)
{
    char character;

    do {
        scanf("%c", &character);
        printf("%c", character);
    } while (character != EOF);
}

I'm going to process the input character by character, and I am only allowed to use scanf(). However, the while loop does not stop. Since I may need to process the input with multiple-line strings, it is impossible to add one more condition: character != '\n'. Can somebody help me with this problem? Thanks!

Upvotes: 0

Views: 604

Answers (2)

Ed Heal
Ed Heal

Reputation: 60047

For a start it should be int main...

Also you need to check the return value from scanf - please read the manual page.

Taking this into account, the code should look like this

#include <stdlib.h>
#include <stdio.h>
int main()
{
    char character;

    while (scanf("%c", &character) == 1) {
       if (character != '\n) {
         printf("%c", character)
       }
    }
    return EXIT_SUCCESS;
}

Upvotes: 1

John Bollinger
John Bollinger

Reputation: 181932

You have an incorrect expectation. When scanf() encounters the end of the input before either matching an input item or recognizing a matching failure, it returns EOF. Under no circumstance does it modify the value of the datum associated with an input item that has not been matched.

You are ignoring scanf's return value, which is generally a perilous thing to do, and instead testing whether scanf records EOF in the object associated with the input item, which, in your particular case, it must not ever do.

Upvotes: 2

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