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C++ Data Types

DoubleDouble

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()

cpp

main.cpp

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:

Data Type Range Precision
float ±1.2e-38 to ±3.4e+38 7 decimal digits
double ±2.2e-308 to ±1.8e+308 15 decimal digits
long double depends on a system but huge from 15 to 33 depending on a system

Tarea

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.

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.

¿Todo estuvo claro?

Sección 2. Capítulo 5
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course content

Contenido del Curso

C++ Data Types

1. Introduction

OverviewArithmetic OperationsDivision int and doubleMath in C++Specifying a Type

2. Numerical Data Types

IntegersUsing IntegersType modifierFloatDoubleNumerical Data Types Summary

3. Text Data Type

CharStringIndexing a StringWorking With StringChanging The String PracticeFinding Text in a StringStrings in Memory

4. Other Data Types and Concepts

BooleanBoolean ExpressionsvoidAuto UnsignedImplicit Type ConversionExplicit Type Conversion

C++ Data Types

DoubleDouble

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()

cpp

main.cpp

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:

Data Type Range Precision
float ±1.2e-38 to ±3.4e+38 7 decimal digits
double ±2.2e-308 to ±1.8e+308 15 decimal digits
long double depends on a system but huge from 15 to 33 depending on a system

Tarea

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.

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.

¿Todo estuvo claro?

Sección 2. Capítulo 5
toggle bottom row
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