scanf before printf - C

Question

So, I have a printf, that asks for the users middle initial, then I have a scanf under that, then I output the users middle initial. My problem is that my printf is displaying after my scanf

C Code

#include <stdio.h>
#include <string.h>

int main(void) {
    char middleInitial;

    printf("What is your middle initial? ");

    scanf(" %c", &middleInitial);

    printf("Middle initial %c", middleInitial);

}

So as you can see, there are two printf's. My scanf is running before my first printf displays the question.

Example (This is what I'm getting in my terminal)

$ ./a.exe
c
What is your middle initial? Middle initial c

What I want

$ ./a.exe
What is your middle initial? c
Middle initial c

By the way, the c is what the user inputs

printf uses `buffered I/O`, so in this case the buffer won't be automatically flushed because there's not a newline in your format string you pass into printf. — bruceg, Apr 14 '17 at 01:08
Possible duplicate of [C/C++ printf() before scanf() issue](https://stackoverflow.com/questions/16877264/c-c-printf-before-scanf-issue) — underscore_d, Aug 22 '19 at 14:03

score 3 · Accepted Answer · edited Apr 14 '17 at 01:11

3

Call fflush(stdout) before your call to scanf().

edited Apr 14 '17 at 01:11

Selman Genç

100,147
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answered Apr 14 '17 at 01:05

DiegoSunDevil

116
4

Answer explains what to do, but not why. Answer would benefit with such an explanation. – chux - Reinstate Monica Apr 14 '17 at 04:23
1

because there's no '\n' in the printf (done on purpose), the buffer doesn't get automatically flushed - it needs to be explicitly. – DiegoSunDevil Apr 14 '17 at 21:20
3

Note: even with a `'\n'`, `printf()` is [not specified](http://stackoverflow.com/q/39536212/2410359) to flush the output either, although that commonly does flush `stdout`. – chux - Reinstate Monica Apr 14 '17 at 23:28

score 0 · Answer 2 · answered Jul 26 '21 at 16:45

0

type fflush(stdout); just before your first scanf() should be after first printf()

In my windows pc I face the same issue. If you use different operating system you might not need it.

answered Jul 26 '21 at 16:45

Calvin Vadakkan

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Please provide a detailed explanation to your answer, in order for the next user to understand your answer better. – Elydasian Jul 27 '21 at 08:27

scanf before printf - C

2 Answers2

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