How to write a program to multiply a number by 4 using a bitwise operator ?

/* Part of this program copied from http://www.sanfoundry.com/c-program-multiply-number-4-using-bitwise-operators/ */

#include <stdio.h>

multbitwise()
{

long number;
printf("Enter an integer: ");
scanf("%ld",&number);
number = number << 2;
printf("Result is %ld \n",number);
}

/* http://stackoverflow.com/questions/4456442/interview-multiplication-of-2-integers-using-bitwise-operators */
/* http://www.geeksforgeeks.org/multiply-two-numbers-without-using-multiply-division-bitwise-operators-and-no-loops/ */
/* http://en.wikipedia.org/wiki/Bitwise_operation */