CPP Language / Variables, Data Types and Constants

Variable
It is a data named used to store a data value.

Syntax of Variable declaring
data_type variable1_name = value1, variable2_name = value2;

Example
int n1=20, n2=100;

Data Types
It is an attribute of data which tells the compiler / interpreter how the programmer intends to use the data.

Data Type Size in Bytes Range
short int 2 -32,768 to 32,767
unsigned short int 2 0 to 65,535
unsigned int 4 0 to 4,294,967,295
int 4 -2,147,483,648 to 2,147,483,647
long int 4 -2,147,483,648 to 2,147,483,647
unsigned long int 4 0 to 4,294,967,295
long long int 8 -(2^63) to (2^63)-1
unsigned long long int 8 0 to 18,446,744,073,709,551,615
signed char 1 -128 to 127
unsigned char 1 0 to 255
float 4
double 8
long double 12
wchar_t 2 or 4 1 wide character

Constants
Constants are to fixed values they don’t change during the execution of a program.

Defining Constants are of 2 types
1. Using #define preprocessor.
#include
using namespace std;
#define LENGTH 10
#define WIDTH 5
int main()
{
int area;
area = LENGTH * WIDTH;
cout << area;
return 0;
}
Output:50

2. Using const keyword.
const type variable = value;

#include
using namespace std;
int main()
{
const int LENGTH = 10;
const int WIDTH = 5;
int area;
area = LENGTH * WIDTH;
cout << area;
return 0;
}
Output:50


Type of Constants Details Example
Integer It can be decimal, octal, or hexadecimal Constant 85 // decimal
0213 // octal
0x4b // hexadecimal
30 // int
30u // unsigned int
30l // long
30ul // unsigned long
Floating point It has an integer part, a decimal point, a fractional part, and an exponent part
and represented in decimal / exponential form. The signed exponent is
introduced by e or E.
3.14159, 314159E-5L
Boolean It consists of either true / 1 or false / 0 either true or false
Character It is enclosed in single quotes. 'x'
String It is enclosed in double quotes. hello Wisdom Materials",



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