This is my first post

Posted by Bartosz Stempień on April 20, 2019 · 5 mins read

Hello everyone!
This is my first post on the blog.
So let’s start. Today we will discuss the most basic data types.
There are seven primitive data types:

Data type Size (bytes) Describe
int 4 only integer numbers
float 4 floating-point numbers
double 8 floating-point numbers
bool 1 it represents true or false (1 or 0)
void 0 no value: using with function which returns nothing
character 1 using for letters, also numbers as character
wide character 2/4 larger character

Each of them consume memory of your computer. It is up to two things: data type and modifiers.
There are four data modifiers in C++:
· signed
· unsigned
· short
· long

Signed: Some ot data type are signed default for example char.
Unsigned: When you know that you don’t need to negative numbers in your data type you can use keyword unsinged. It has huge advantage: you can increase the max range of positive number (the range will be from 0 to [max_positive_range + max_negative_range] or [max_positive_range * 2 + 1]. For example if you are calculating the numbers of factorial you know that there are only positive numbers. With keyword you can store more numbers without getting more memory for variable.
Short: It reduces the range of number of variable and the size of variable.
Long: Use it when you want to increase range of number: negative and positive numbers range.

C++ allows you to combine the propertly data modifiers with each others. For example you can write: long long int or unsigned long long int.

In the table below I present two data types with modifiers and how many memory they consume:

Data type Size (bytes) Range
short int 2 -32,768 to 32,767
int 4 -2,147,483,648 to 2,147,483,647
unsigned int 4 0 to 4,294,967,295
long int 4 -2,147,483,648 to 2,147,483,647
long long int 8 -(2^63) to 2^63
unsigned long long int 8 0 to 18,446,744,073,709,551,615
char 1 -128 to 127
signed char 1 -128 to 127
unsigned char 1 0 to 255

If you want to see how much of memory takes your variable you cant use ‘sizeof’.

#include <iostream>
int main()
{
  int a; //declaration of variable 
  std::cout << sizeof(a) << std::endl; // or you can write just cout/endl if you are using "namespace std"
  return EXIT_SUCCESS;
}

There is a way to see the range of data types too:

#include <iostream>
#include "limits.h"
int main()
{
  int a; //declaration of variable 
  std::cout << sizeof(a) << std::endl; // or you can write just cout/endl if you are using "namespace std"
  std::cout << INT_MIN << std:: endl; // the min range of int
  std::cout << INT_MAX << std:: endl; // tha max range of int
  return EXIT_SUCCESS;
}

Useful links:
There you can read more:
LIMITS
ASCII

Next Post →