Variables, Constant and Literals in C++

In this article, we will discuss variables, constants, and literals in C++ programming language with examples.

C++ Variables

In programming, variables are containers for storing data values. It is basically a name given to a memory location and this name must be unique, you cannot use the same variable name for two different memory locations. The value that you will store in a variable can be changed during the execution of the program.

syntax: data_type variable_name;
example: int count = 10;

Variables in C++

Rules for deciding a variable name:

A variable name can contain only alphabets, digits, and underscores.
A variable name must begin with an alphabet or underscore, it cannot begin with a number.
A variable name should not contain any whitespace or special characters like #, $, @, %, *, etc.
A variable name is case-sensitive in nature. Ex: num and Num is two different variables.
One cannot use C++ reverse keywords (Ex: int, float, for) as a variable name.

Note: It is suggested to start a variable name with lowercase alphabets and try to give always meaningful variable names. (alert-success)

C++ Constant

In C++ programming, constants are those kinds of variables whose values are fixed and cannot be changed. These kinds of variables are defined using the const keyword and they have read-only property. Example:

const float PI = 3.14
PI = 3.141 //Error: value of PI is constant

C++ Literals

Values such as numbers, characters, or strings of characters whose values are self-evident are known as literals. These values you can use directly in your C++ code. Example: 4, 5.6, 'c', 3.14156e3, 0x19, etc.

Different kinds of literals present in C++ programming:

1. Integer Literals: Integer literals are those numbers that do not have any decimal point or exponential part. We can write an integer literal using decimal, octal or hexadecimal notation.

Decimal (base 10): It is the Normal representation of numbers that we use in daily life. Ex: 25
Octal (base 8): Integer literals that begin with 0 are interpreted as octal. Ex: 031 is an octal representation of 25.
Hexadecimal (base 16): Integer literals that begin with 0x or 0X are interpreted as hexadecimal. Ex: 0x19 is a hexadecimal representation of 25.

//C++ example of Integer Literals
#include<iostream>
using namespace std;

int main()
{
    int x, y, z;
    x = 25;
    y = 031;
    z = 0x19;

    cout<<"Decimal Representation: "<<x<<endl;
    cout<<"Octal Representation: "<<y<<endl;
    cout<<"Hexadecimal Representation: "<<z<<endl;

    return 0;
}

Output:

Decimal Representation: 25
Octal Representation: 25
Hexadecimal Representation: 25

In the above code, you can observe that all three different integer variables represent the same value 25 in C++ programming.

2. Floating point Literals: Floating-point literals include either a decimal point or an exponent (indicated by either E or e) that is specified using scientific notation.

Example:
3.52341
3.52341E2 = 3.52341x10^2 = 352.341
3.52341e2 = 3.52341x10^2 = 352.341
3.52341E-1 = 3.52341x10^-1 = 0.352341

//C++ example of Floating Point Literals
#include<iostream>
using namespace std;

int main()
{
    float x, y, z, n;
    x = 3.52341;
    y = 3.52341E2;
    z = 3.52341e3;
    n = 3.52341E-1;

    cout<<x<<endl;
    cout<<y<<endl;
    cout<<z<<endl;
    cout<<n<<endl;

    return 0;
}

Output:

3. Character Literals: A character enclosed with single quotes are known as a character literal. Ex: 'a', '4', '{', etc.

4. String Literals: When zero or more characters are enclosed in double quotation marks is known as a string literal. Ex: "fruit", "code", " ", "c", "\nHello World", etc.

Note: The compiler appends a null character ('\0') to every string literal. Thus, the actual size of a string literal is one more than its apparent size. (alert-success)

You can read our article, character vs string class in C++ to understand the difference between them.

(getButton) #text=(Escape Sequences in C++.) #icon=(link) #color=(#2339bd)

Variables, Constant and Literals in C++

C++ Variables

C++ Constant

C++ Literals

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