Question

1. Write a regular expressions that would match lines in text that contain word DATE: at the beginning of a line followed by actual date in format YYYY-MM-DD. Space between colon ( : ) and date may or may not exist.
2. In C, if you issue the following statement n << 2 where n is an integer, what will be value of n?

Answer 1

Regular Expression to validate Date:YYYY-MM-DD is

([D][a][t][e][:][12]\d{3}-(0[1-9]|1[0-2])-(0[1-9]|[12]\d|3[01]))

Java program used for varify:

public class Main
{
        public static void main(String[] args) {
           String str="Date:2016-11-15";
                System.out.println(str.matches("([D][a][t][e][:][12]\\d{3}-(0[1-9]|1[0-2])-(0[1-9]|[12]\\d|3[01]))"));
        }
}

Varify in java: (Note: In program we use \\d instead of \d because if we use only \d compiler take it as a space character)

Output 1:

Output 2:

Output 3:

Output 4:

Answer 2:

In c << is a left shift operator.

n<<c is equivalent to multiplying n with 2^c

Suppose value of c=2 and value of n=4

then it is 4*2² =4*4=16

C program used for varify:

#include <stdio.h>

int main()
{
   int n=4;
   printf("value of n<<2 is %d",n<<2);
   

    return 0;
}

Output 1: (here value of n is taken 0 by default by compiler)

So it solve like: 0*2²=0

Output 2: