What happens if C tries to scan character in integer variable [duplicate]

Answer 1

Check the return of scanf(). When you type in characters, the correspond result will occur.

if (1 == scanf("%d", &number)) {
  printf("The result is:%d", number);
}
else {
  printf("Invalid data entered.  `number` not changed\n");
}

Note: Code's int number; is not initialized, so its value could be any int. With invalid input, number was not changed and code printed the uninitialized number which just happeded to have the value of "1986895412". It may differ tomorrow.

Note: leading space in " %d" is not needed as %d itself consume leading whitespace.