Issue with scanf() in C

Question

I am learning by myself how to code using the C languange. In order to study this latter a bit more in depth, I'm doing some basic exercises and, due to this, today I have faced a little issue using the scanf() instruction. Infact, the following code:

int main() { char inputOne; char inputTwo; printf("Insert a char: "); scanf("%c", &inputOne); // &inputOne is the pointer to inputOne. printf("Insert another char: "); scanf("%c", &inputTwo); if (inputOne == inputTwo) { printf("You have inserted the same char!\n"); printf("Chars inserted: %c, %c\n", inputOne, inputTwo); } else { printf("You have inserted two different chars!\n"); printf("Chars inserted: %c, %c\n", inputOne, inputTwo); } }

when compiled does not return any error, but when I launch the application on the Terminal, I am not able to insert the second character. Here is an example of what happens:

Macbook-Pro-di-Rodolfo:~ Rodolfo$ /Users/Rodolfo/Documents/GitHub/Fondamenti\ di\ C/esempio-if-else ; exit; Insert a char: a Insert a second char: You have inserted two different chars! Chars inserted: a, logout [Process completed]

Can anybody explain me why this happens?

One of the hundreds of duplicates of this question can be found here. — WhozCraig
– WhozCraig, Commented Oct 8, 2016 at 18:29
@user3121023 do the number of spaces before or after the conversion specification influence the final result? With other words, are scanf(" %c", &inputTwo) and scanf(" %c", &inputTwo) identical for the compiler? — rudicangiotti
– rudicangiotti, Commented Oct 9, 2016 at 23:21
@user3121023 I'm sorry, it is not properly visible in my first comment but I was meaning if scanf() behaves in the same way indipendently from the number of white spaces between the quotation mark and the conversion specification %. In other words, if <space><space><space>%c and <space>%c outputs the same stuff. — rudicangiotti
– rudicangiotti, Commented Oct 10, 2016 at 11:31

shiva · Accepted Answer · 2016-10-08 18:32:39Z

It takes line feed as input to the second character. You can take the inputTwo again to prevent it:

int main() { char inputOne; char inputTwo; printf("Insert a char: "); scanf("%c", &inputOne); // &inputOne is the pointer to inputOne. printf("Insert another char: "); scanf("%c", &inputTwo); scanf("%c", &inputTwo); if (inputOne == inputTwo) { printf("You have inserted the same char!\n"); printf("Chars inserted: %c, %c\n", inputOne, inputTwo); } else { printf("You have inserted two different chars!\n"); printf("Chars inserted: %c, %c\n", inputOne, inputTwo); } }

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