Who to check if an input is left blank

Question

For example:
int i;
scanf("%d", &i);
This will inquire user for an input. If this is left blank, this will generate error if used in any function. So how can i check if input is blank?
(So that I can replace that with my error handler)

Answer 1

When you use scanf but user does not input anything then scanf will return a negative value.
So you use use if statement to check if there was any input or not.
Example:
#include <stdio.h>
int main() {
int foo;
if (scanf("%d", &foo) > 0) {
printf("Input = %d", foo);
} else {
printf("No input");
}
return 0;
}

Answer 2

https://www.tutorialspoint.com/c_standard_library/c_function_scanf.htm

Answer 3

🔫 Rick Grimes does the same apply for 'char' value?
Like:
char test_char;