C: scanf for char not working as expected [duplicate]

Answer 1

You have to change

scanf("%c", &d);

to

scanf(" %c", &d);
       ^
       |

Otherwise, scanf() will consider the previously entered ENTER key press.

Note:

1. ENTER key press generates a \n, which is a vaild input for %c format specifier. Adding a space before %c tells scanf() to ignore all leading whitespace-like inputs (including that previously stored \n) and read the first non-whitespace character from stdin.

2. As for the case with %d format specifier, it consumes (and ignores) any leading whitespace-like inputs before scanning for numeric inputs, so the second case does not suffer any issues.