# Values and Variables in c++

#### Values and Variables in c++

In this chapter we explore some building blocks that are used to develop C++ programs.

#### Integer Values

The number four (4) is an example of a numeric value. In mathematics, 4 is an integer value. Integers are whole numbers, which means they have no fractional parts, and an integer can be positive, negative, or zero. Examples of integers include 4,−19, 0, and−1005.

#### Code Example

``````#include <iostream>
int main()
{
std::cout << 4 << '\n';
}``````
``std::cout << "4\n";``

sends one thing to the output stream, the string”4\n”. The statement

std::cout << 4 << ‘\n’;

sends two things to the output stream, the integer value 4 and the newline character’\n’.

``````#include <iostream>
int main()
{
std::cout << -3000000000 << '\n';
}``````
``output  1294967296``

#### Variables and Assignment

In algebra, variables are used to represent numbers.

``````#include <iostream>
int main()
{
int x; x = 10; std::cout << x << '\n';
}``````
``int x; ``

This is a declaration statement. All variables in a C++ program must be declared. A declaration speciﬁes the type of a variable. The word int indicates that the variable is an integer. The name of the integer variable is x. We say that variable x has type int.

``````#include <iostream>
int main()
{
int x;
x = 10;
std::cout << x << '\n';
x = 20;
std::cout << x << '\n';
x = 30;
std::cout << x << '\n';
}``````
``````int x = 0;
int y;
int z = 5;``````

In the case of multiple declaration statements the type name (hereint) must appear in each statement. The compiler maps a variable to a location in the computer’s memory. We can visualize a variable and its corresponding memory location as a box.