%d
prints an integer: it will print the ascii representation of your character. What you need is %c
:
printf("%c", ch);
printf("%d", '\0');
prints the ascii representation of '\0'
, which is 0 (by escaping 0 you tell the compiler to use the ascii value 0.
printf("%d", sizeof('\n'));
prints 4 because a character literal is an int
, in C, and not a char
.