C: scanf() inside a loop

Question

This program doesn't seem to accept input at every iteration of the while loop, when ideally it should.However when I replace the %c parameter of the scanf() function with %d ( i.e an integer input rather than a char input) it seems to just work absolutely fine, which input accepted for every iteration of the while loop. Why do I see this discrepancy ?

int main()
{
    char grade;
    int i=0;

    while(i<10){
        printf("Enter ur grade\n");
        scanf("%c", &grade);
        switch(grade){
            case 'A' : printf("U R THE BEST\n");
                       break;
            case 'B' : printf("U R VERY GOOD DUDE...\n");
                       break;
            case 'C' : printf("U R GOOD DUDE...\n");
                       break;
            case 'D' : printf("U R Not good DUDE...\n");
                       break;
            case 'E' : printf("U R WORST DUDE...\n");
                       break;
            default  : printf("U r AWESOME...\n");
                       break;
        }
    i++;
}

Can you give an example of the input and the output you get? — DJ Burb, Oct 01 '14 at 16:06
scanf doesn't remove newline from input buffer. many dups on SO: http://stackoverflow.com/questions/13275417/why-scanfd-does-not-consume-n-while-scanfc-does (not really dupe but solution to your problem) — Adriano Repetti, Oct 01 '14 at 16:07
Every time you input a char (you are actually inputting two chars), there's a newline (`\n`) char left in the input stream, which is consumed in the next iteration. You need to clear it with `getchar()` or similar techniques. — P.P, Oct 01 '14 at 16:07
Your braces don't balance. Also what's wrong with `for(int i = 0; i < 10; ++i)`? — Bathsheba, Oct 01 '14 at 16:13

Spikatrix · Answer 1 · 2014-10-01T16:45:30.190

-1

Add a space before the %c of the scanf. This is done to remove all blanks from the stdin before scanning a character. scanf does not take the \n(enter key) character after entering a character and leaves it in the buffer which is taken when scanf is called again.

Another thing: you forgot to put one } in your code.

edited Oct 01 '14 at 16:45

answered Oct 01 '14 at 16:15

Spikatrix

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Rustam · Answer 2 · 2014-10-01T16:27:21.230

-1

try this : put a space before %c it is because it stores \n too.

 scanf(" %c", &grade);

edited Oct 01 '14 at 16:27

answered Oct 01 '14 at 16:21

Rustam

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C: scanf() inside a loop

2 Answers2