DOUBLE TYPE IN C

High-precision floating-point data or numbers (up to 15 or 17 digits) can be stored using the double data type in the C programming language. Large decimal number values are stored there.

The stored numbers are twice as large as the maximum amount of data that may be stored in a float data type. It is called a double data type as a result.

In C, any variable declared with the double data type has a 64-bit (or 8-byte) size.

Note:

• In the double data format, the sign representation uses one bit, the exponent uses one bit, and the mantissa uses the remaining 52 bits.
• Between 1.7E-308 and 1.7E+308, the double in c can be found. Real numbers, decimals, negative values, and other types of data can all be represented by a double.

Double Variable Declaration Syntax:

double var_name;

The double keyword is used to declare the double variables in the language of C, followed by the variable name.

Double Variable Initialization:

For a variable to have a specific value, we must initialise the double variable with that specific value because when a variable is declared, it often has a garbage value.

In C, there are two methods for initializing a double:

Method 1- By utilizing the assignment operator to assign a value to the declared double variable:

double quantity;

quantity = 2.50;

Method 2- By using the assignment operator to the double variable during the declaration to assign it a value:

double quantity = 2.50;

Double example in C:

double temp_1 = 8.4;

double temp_2;

double temp_3;

temp_3 = 7.8;

In the aforementioned illustration, temp_1 is declared and given the value 8.4. Temp_2 is specified but not given a value, so it will have a trash value, and Temp3 is declared but not given a value, so it also has a garbage value but is later given the value 7.8.

Printing the Double value in C:

In C, a double can be printed using both %f and %lf. The format specifiers %f and %lf both stand for float and double, respectively. The printf() function in C respects double and float data equally.

#include <stdio.h>

int main()

{

    double temp_1 = 8.4;

    double temp_2;

    double temp_3;

    temp_3 = 7.8;

    printf("Value of the temp_1 = %lf\n",temp_1);

    printf("Value of the temp_2 = %f\n",temp_2);

    printf("Value of the temp_3 = %f\n",temp_3);   

}

OUTPUT:

Double Representation in C:

• The way the double is implemented in the code determines how precise it is in C. The IEEE-754 standard is typically used by modern compilers.
• The Institute of Electrical and Electronics Engineers (IEEE) created the IEEE Standard for Floating-Point Arithmetic (IEEE 754) in 1985 as a technical standard for floating-point calculation.
• The standard addressed a number of issues that were present in the various floating-point implementations and restricted their portability and reliability.

The following is how 64-bit representation of numbers is done in such compilers:

• For the sign, the first bit is there.
• 52 bits of significand (mantissa) are used, with 0 denoting the positive and 1 the negative.
• The exponent is 11 bits.
• Up to 15 or 16 digits of value can be stored.

Some Double Date Type Programs in C:

1. A Program to Convert Feet into Meters the Double Data Type is Used  

#include <stdio.h>

// function

double feet_To_Meter (double feet)

{

    return feet / 3.28;

}

int main()

{

    double feet;

    double meter;

    printf ("Enter the value in feet: ");

    scanf("%lf", &feet);

    // Calling a function

    meter = feet_To_Meter(feet);

    printf (" The value in meter for the given feet is: %lf", meter);

    return 0;

}

OUTPUT:

Explanation:

The function 'function_To_Meter', which accepts a double value as an argument, has been defined in the code above. The feet value is converted into a meter and returned using the formula feet / 3.28.

2. Program to Convert an Integer Data Type in to a Double Data Type:

#include <stdio.h>

int main()

{

    // declaration of variables of int data type

    int numerator = 11, denominator = 4;

    // declaration of variables of double data type

    double remainder;

    // calculation and storing the remainder

    remainder = (double) numerator / denominator;

    // printing output

    printf ("Output: %lf \n", remainder);

}

OUTPUT:

Explanation:

• The numerator and denominator in the example above are both of the integer type. The remaining variable of the double type has been created.
• Integer values will be output by the numerator and denominator as integer and integer, respectively.
• So, using the (double) numerator, we will change the numerator's data type to a double. The double value that is now returned by the numerator/denominator can be kept in the remainder.

3. Program to Convert Temperatures from Celsius to Fahrenheit:

#include <stdio.h>

int main()

{

    // declaration of two double variables

    double cel_temp, fahren_temp;

    printf(" Celsius Temperature: ");

    scanf (" %lf", &cel_temp);

    // conversion of celsius to fahrenheit

    fahren_temp  = ( cel_temp * 1.8) + 32;

    printf (" Fahrenheit Temperature is: %lf", fahren_temp);

    return 0;

}

OUTPUT:

Conclusion:

• In C, high-precision floating-point data or numbers are stored using the double.
• The double in C falls within the range of 5.0 10345 to 1.7 10308.
• The C double may store between 15 and 17 digits.
• The way the code is implemented determines the precise double precision.