Зміст курсу

C++ Data Types

1. Introduction

Overview Arithmetic Operations Division int and double Math in C++Specifying a Type

2. Numerical Data Types

Integers Using Integers Type modifier Float Double Numerical Data Types Summary

3. Text Data Type

Char String Indexing a String Working With String Changing The String Practice Finding Text in a String Strings in Memory

4. Other Data Types and Concepts

Boolean Boolean Expressions Void Auto Unsigned Implicit Type Conversion Explicit Type Conversion

Double

As you saw in the previous task, float's precision (7 decimal digits) is not always enough. But C++ has a solution: double. With a precision of 15 decimal digits, it is much more accurate than float. The syntax of using double is the same as always:

By default, cout prints floating-point numbers with a precision of 6 significant digits. That way, you won't see a difference between float and double. To set a larger precision, we can use std::cout << std::setprecision(15); again (this will set the precision to 15 significant digits).

Note
Don't forget to include <iomanip> to be able to use std::setprecision()

main


              123456789101112131415
            
#include <iostream>
#include <iomanip>

int main()
{
  	float pi_float = 3.14159265358979;
	double pi_double = 3.14159265358979;
	
    std::cout << "float pi: " << pi_float << std::endl;
    std::cout << "double pi: " << pi_double << std::endl;
    
    std::cout << std::setprecision(15);
    std::cout << "float pi with setprecision: " << pi_float << std::endl;
    std::cout << "double pi with setprecision: " << pi_double << std::endl;
}

How is better precision achieved in <code class="go3679463865">double</code>?

It just takes up more memory. A float type takes up 4 bytes, and a double takes up 8 bytes of memory.

There also is a long double type. Its size ranges from 8 bytes (just like a double) to 16 bytes. You can check the size of the long double on your system by using the following code:

Additionally, you should add L to a value you are assigning (otherwise, the value will be assigned with the precision of double). Look at the example:

Here is a little summary:

Завдання

You need to calculate (1/3)² using different data types. For that, assign the value of 1/3 to the float, double, and long double typed variables.
Then print those numbers multiplied by themselves, for example:

Steps:

Initialize a float variable with the value 1/3.;
Initialize a double variable with the value 1/3.;
Initialize a long double variable with the value 1/3.L.
note: long double takes up 16 bytes of memory on our system
Set the precision of output to 25 decimals with setprecision(25);
Print all those values multiplied by themselves.

Завдання

Steps:

Initialize a float variable with the value 1/3.;
Initialize a double variable with the value 1/3.;
Initialize a long double variable with the value 1/3.L.
note: long double takes up 16 bytes of memory on our system
Set the precision of output to 25 decimals with setprecision(25);
Print all those values multiplied by themselves.

Note
If you got zeros in the output, make sure you assigned the values exactly like shown above (1/3., 1/3.L).
We will discuss the reasons for this behavior in the Arithmetic Operations chapter.

Все було зрозуміло?

Секція 2. Розділ 5

Double

Note
Don't forget to include <iomanip> to be able to use std::setprecision()

main


              123456789101112131415
            
#include <iostream>
#include <iomanip>

int main()
{
  	float pi_float = 3.14159265358979;
	double pi_double = 3.14159265358979;
	
    std::cout << "float pi: " << pi_float << std::endl;
    std::cout << "double pi: " << pi_double << std::endl;
    
    std::cout << std::setprecision(15);
    std::cout << "float pi with setprecision: " << pi_float << std::endl;
    std::cout << "double pi with setprecision: " << pi_double << std::endl;
}

How is better precision achieved in <code class="go3679463865">double</code>?

It just takes up more memory. A float type takes up 4 bytes, and a double takes up 8 bytes of memory.

There also is a long double type. Its size ranges from 8 bytes (just like a double) to 16 bytes. You can check the size of the long double on your system by using the following code:

Additionally, you should add L to a value you are assigning (otherwise, the value will be assigned with the precision of double). Look at the example:

Here is a little summary:

Завдання

Steps:

Initialize a float variable with the value 1/3.;
Initialize a double variable with the value 1/3.;
Initialize a long double variable with the value 1/3.L.
note: long double takes up 16 bytes of memory on our system
Set the precision of output to 25 decimals with setprecision(25);
Print all those values multiplied by themselves.

Завдання

Steps:

Initialize a float variable with the value 1/3.;
Initialize a double variable with the value 1/3.;
Initialize a long double variable with the value 1/3.L.
note: long double takes up 16 bytes of memory on our system
Set the precision of output to 25 decimals with setprecision(25);
Print all those values multiplied by themselves.

Note
If you got zeros in the output, make sure you assigned the values exactly like shown above (1/3., 1/3.L).
We will discuss the reasons for this behavior in the Arithmetic Operations chapter.

Все було зрозуміло?

Секція 2. Розділ 5

Double

Note
Don't forget to include <iomanip> to be able to use std::setprecision()

main


              123456789101112131415
            
#include <iostream>
#include <iomanip>

int main()
{
  	float pi_float = 3.14159265358979;
	double pi_double = 3.14159265358979;
	
    std::cout << "float pi: " << pi_float << std::endl;
    std::cout << "double pi: " << pi_double << std::endl;
    
    std::cout << std::setprecision(15);
    std::cout << "float pi with setprecision: " << pi_float << std::endl;
    std::cout << "double pi with setprecision: " << pi_double << std::endl;
}

How is better precision achieved in <code class="go3679463865">double</code>?

It just takes up more memory. A float type takes up 4 bytes, and a double takes up 8 bytes of memory.

There also is a long double type. Its size ranges from 8 bytes (just like a double) to 16 bytes. You can check the size of the long double on your system by using the following code:

Additionally, you should add L to a value you are assigning (otherwise, the value will be assigned with the precision of double). Look at the example:

Here is a little summary:

Завдання

Steps:

Initialize a float variable with the value 1/3.;
Initialize a double variable with the value 1/3.;
Initialize a long double variable with the value 1/3.L.
note: long double takes up 16 bytes of memory on our system
Set the precision of output to 25 decimals with setprecision(25);
Print all those values multiplied by themselves.

Завдання

Steps:

Initialize a float variable with the value 1/3.;
Initialize a double variable with the value 1/3.;
Initialize a long double variable with the value 1/3.L.
note: long double takes up 16 bytes of memory on our system
Set the precision of output to 25 decimals with setprecision(25);
Print all those values multiplied by themselves.

Note
If you got zeros in the output, make sure you assigned the values exactly like shown above (1/3., 1/3.L).
We will discuss the reasons for this behavior in the Arithmetic Operations chapter.

Все було зрозуміло?

Note
Don't forget to include <iomanip> to be able to use std::setprecision()

main


              123456789101112131415
            
#include <iostream>
#include <iomanip>

int main()
{
  	float pi_float = 3.14159265358979;
	double pi_double = 3.14159265358979;
	
    std::cout << "float pi: " << pi_float << std::endl;
    std::cout << "double pi: " << pi_double << std::endl;
    
    std::cout << std::setprecision(15);
    std::cout << "float pi with setprecision: " << pi_float << std::endl;
    std::cout << "double pi with setprecision: " << pi_double << std::endl;
}

How is better precision achieved in <code class="go3679463865">double</code>?

It just takes up more memory. A float type takes up 4 bytes, and a double takes up 8 bytes of memory.

There also is a long double type. Its size ranges from 8 bytes (just like a double) to 16 bytes. You can check the size of the long double on your system by using the following code:

Additionally, you should add L to a value you are assigning (otherwise, the value will be assigned with the precision of double). Look at the example:

Here is a little summary:

Завдання

Steps:

Initialize a float variable with the value 1/3.;
Initialize a double variable with the value 1/3.;
Initialize a long double variable with the value 1/3.L.
note: long double takes up 16 bytes of memory on our system
Set the precision of output to 25 decimals with setprecision(25);
Print all those values multiplied by themselves.

Note
If you got zeros in the output, make sure you assigned the values exactly like shown above (1/3., 1/3.L).
We will discuss the reasons for this behavior in the Arithmetic Operations chapter.

Секція 2. Розділ 5

Перейдіть на комп'ютер для реальної практикиПродовжуйте з того місця, де ви зупинились, використовуючи один з наведених нижче варіантів