Question

Please complete the following problem in C. No source code is provided.

The left-shift operator can be used to pack four character values into a four-byte unsigned int variable. Write a program that inputs four characters from the keyboard and passes them to function packCharacters. To pack four characters into an unsigned int variable, assign the first character to the unsigned int variable, shift the unsigned int variable left by 8 bit positions and combine the unsigned variable with the second character using the bitwise inclusive OR operator. Repeat this process for the third and fourth characters. The program should output the characters in their bit format before and after they’re packed into the unsigned int to prove that the characters are in fact packed correctly in the unsigned int variable.

Answer 1

Packed Characters in an Integer:

• First ofall, the Program needs to accept character input from keyboard and store in packCharacters.
• And, the Output should be the characters in their bit format before and after they are packed in to the unsigned integer to prove they are packed correctly.    

/*Source Code*/

#include<stdio.h>

unsigned packCharacters(unsigned c1, char c2);

void display(unsigned val);

int main(void)

{

      char a;

      char b;

      char d;

      char e;

      unsigned result;

      unsigned result1;

      unsigned result2;

      printf("Enter any four characters:\n\n");

      printf("Enter the %s character :", "first");

      scanf("%c", &a);

      getchar();

      printf("Enter the %s character :", "second");

      scanf("%c", &b);

      getchar();

      printf("Enter the %s character :", "third");

      scanf("%c", &d);

      getchar();

      printf("Enter the %s character :", "fourth");

      scanf("%c", &e);

      getchar();

      printf("\nRepresentation of '%c' in bits as an unsigned integer is:\n", a);

      display(a);

      printf("\nRepresentation of '%c' in bits as an unsigned integer is:\n", b);

      display(b);

      printf("\nRepresentation of '%c' in bits as an unsigned integer is:\n", d);

      display(d);

      printf("\nRepresentation of '%c' in bits as an unsigned integer is:\n", e);

      display(e);

      unsigned ch = a;

      result = packCharacters(ch, b);

      result1 = packCharacters(result, d);

      result2 = packCharacters(result1, e);

      printf("\nRepresentation of '%c\''%c\''%c\' and '%c\'"

            "packed in an unsigned integer is:\n", a, b, d, e);

      display(result2);

      getchar();

      return 0;

}

unsigned packCharacters(unsigned c1, char c2)

{

      unsigned pack = c1;

      pack <<= 8;

      pack |= c2;

      return pack;

}

void display(unsigned val)

{

      unsigned c;

      unsigned mask = 1 << 31;

      printf("%7u = ", val);

      for (c = 1; c <= 32; c++)

      {

            val & mask ? putchar('1') : putchar('0');

            val <<= 1;

            if (c % 8 == 0)

            {

                  printf(" ");

            }

      }

      putchar('\n');

}

Sample Design of Output: