Double Given Number without * Operator

Problem Statement:

Program to double the given number without using '*' operator.

Source Code:
#include<stdio.h>
int main(){
    int num;
    scanf("%d",&num);
    printf("%d",num<<1);
    return 0;
}
SAMPLE INPUT1:
8
SAMPLE OUTPUT1:
16

SAMPLE INPUT2:
-5
SAMPLE OUTPUT2:
-10