Do-while cycle scanf reads cycles two times instead of one when reading single character

Question

I have this code :

char c;
do
{
    scanf("%c",&c);
    printf("coucou\n");
} while (c!='q');

And here my result :

Input:

M

Output:

coucou
coucou

Why does it print "coucou" 2 times every time ?

Answer 1

The cycle is executed 2 times because scanf scans 2 characters, one for M and another for the \\n new line character.

You can easily solve this by adding a condition to your cycle:

do
{
  if(getchar() != '\n')  
    printf("coucou\n");
} while (c!='q');