Variables

string aFriend = "Bill";

int a = 18;
int e = (a + b) % c; //% - remainder
int max = int.MaxValue;
int min = int.MinValue;
Console.WriteLine($"The range of integers is {min} to {max}");

Predefined data types

C#	Mono	Signed	Memory	Range
sbyte	System.Sbyte	Yes	1 byte	–128 to 127
short	System.Int16	Yes	2 bytes	–32768 to 32767
int	System.Int32	Yes	4 bytes	–2147483648 to 2147483647
long	System.Int64	Yes	8 bytes	–9223372036854775808 to 9223372036854775807
byte	System.Byte	No	1 byte	0 to 255
ushort	System.Uint16	No	2 bytes	0 to 65535
uint	System.Uint32	No	4 bytes	0 to 4294967295
ulong	System.Uint64	No	8 bytes	0 to 18446744073709551615
float	System.Single	Yes	4 bytes	–1.5x10-45 to 3.4 x x1038
double	System.Double	Yes	8 bytes	–5.0x10-324 to 1.7x10308
decimal	System.Decimal	Yes	12 bytes	1.0x10-28 to 7.9x1028
char	System.Char		2 bytes	Unicode characters
boolean	System.Boolean		1 byte	True or false

Declare int variable:

using System;
class EasyCSharp
{
    public static void Main()
    {
        int i;
        i = 10;
        Console.WriteLine(i);
    }
}