Question

Write a program in C++ that converts decimal numbers to IEEE Standard 754 Floating Point Single Precision.

Please include code that converts to single precision and double precision as a second option.

Answer 1

CODE

#include <iostream>

using namespace std;

void printBinary(int n, int i)

{

  // Prints the binary representation

  // of a number n up to i-bits.

  int k;

  for (k = i - 1; k >= 0; k--) {

    if ((n >> k) & 1)

      printf("1");

    else

      printf("0");

  }

}

typedef union {

  float f;

  struct

  {

    // Order is important.

    // Here the members of the union data structure

    // use the same memory (32 bits).

    // The ordering is taken

    // from the LSB to the MSB.

    unsigned int mantissa : 23;

    unsigned int exponent : 8;

    unsigned int sign : 1;

  } raw;

} myfloat1;

typedef union {

  float f;

  struct

  {

    // Order is important.

    // Here the members of the union data structure

    // use the same memory (32 bits).

    // The ordering is taken

    // from the LSB to the MSB.

    unsigned long mantissa : 52;

    unsigned int exponent : 11;

    unsigned int sign : 1;

  } raw;

} myfloat2;

// Function to convert real value

// to IEEE foating point representation

void printIEEE(myfloat1 var)

{

  // Prints the IEEE 754 representation

  // of a float value (32 bits)

  printf("%d | ", var.raw.sign);

  printBinary(var.raw.exponent, 8);

  printf(" | ");

  printBinary(var.raw.mantissa, 23);

  printf("\n");

}

// Function to convert real value

// to IEEE foating point representation

void printIEEE(myfloat2 var)

{

  // Prints the IEEE 754 representation

  // of a float value (32 bits)

  printf("%d | ", var.raw.sign);

  printBinary(var.raw.exponent, 11);

  printf(" | ");

  printBinary(var.raw.mantissa, 52);

  printf("\n");

}

// Driver Code

int main()

{

  // Instantiate the union

  myfloat1 var1;

myfloat2 var2;

  printf("Enter a decimal number: ");

float num;

scanf("%f", &num);

printf("1. For single precision\n2. For double precision\nEnter your choice: ");

int choice;

scanf("%d", &choice);

if (choice == 1) {

// Get the real value

  var1.f = num;

  // Get the IEEE floating point representation

  printf("IEEE 754 single precision representation of %f is : \n",

    var1.f);

  printIEEE(var1);

}

else if (choice == 2) {

// Get the real value

  var2.f = num;

  // Get the IEEE floating point representation

  printf("IEEE 754 double precision representation of %f is : \n",

    var2.f);

  printIEEE(var2);

}

  return 0;

}