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In general, the increment operator is used to increment the value of a variable and it is denoted by ++. Similar to Java, in C# there are two kinds of increment operations that can be performed -
• Pre-increment operation
• Post-increment operation

Pre-increment operation


Pre-increment operator is named so because the increment operator(++) comes before the operand.
The sequence of operation in pre-increment operation is -
• Firstly, the original value of incremented and,
• Secondly, this incremented value is read or used.



// C# pre-increment operation

using System;

class A
{
public static void Main()
{
	//Local variables
	char ch = 'b';
	byte b = 20;
	short sh = 99;
	int i = 16;
	long l = 99999;
	float f = 20.5f;
	double d = 15.5;

	Console.WriteLine("Original character " + ch);
	Console.WriteLine("Incremented character " + ++ch);

	Console.WriteLine("Original byte " + b);
	Console.WriteLine("Incremented byte " + ++b);

	Console.WriteLine("Original short " + sh);
	Console.WriteLine("Incremented short " + ++sh);

	Console.WriteLine("Original int " + i);
	Console.WriteLine("Incremented int " + ++i);

	Console.WriteLine("Original long " + l);
	Console.WriteLine("Incremented long " + ++l);

	Console.WriteLine("Original float " + f);
	Console.WriteLine("Incremented float  " + ++f);

	Console.WriteLine("Original double " + d);
	Console.WriteLine("Incremented double " + ++d);
}
}





Output is




Original character a
Incremented character b
Original byte 10
Incremented byte 11
Original short 100
Incremented short 101
Original int 10
Incremented int 11
Original long 99999
Incremented long 100000
Original float 20.5
Incremented float  21.5
Original double 15.5
Incremented double 16.5








Post-increment operator



Post-increment operation is named so because the increment operator(++) comes after the operand.
In a post increment operation, the sequence of operation is -
• Firstly, the original value of operand is read or used and,
• Secondly, this original value is incremented.



// C# post-increment operation

using System;

class A
{
public static void Main()
{
	//Local variables
	char ch = 'b';
	byte b = 20;
	short sh = 99;
	int i = 16;
	long l = 99999;
	float f = 20.5f;
	double d = 15.5;

	Console.WriteLine("Original character " + ch);
	Console.WriteLine("Incremented character " + ch++);

	Console.WriteLine("Original byte " + b);
	Console.WriteLine("Incremented byte " + b++);

	Console.WriteLine("Original short " + sh);
	Console.WriteLine("Incremented short " + sh++);

	Console.WriteLine("Original int " + i);
	Console.WriteLine("Incremented int " + i++);

	Console.WriteLine("Original long " + l);
	Console.WriteLine("Incremented long " + l++);

	Console.WriteLine("Original float " + f);
	Console.WriteLine("Incremented float  " + f++);

	Console.WriteLine("Original double " + d);
	Console.WriteLine("Incremented double " + d++);
}
}





Output -




Original character a
Incremented character a
Original byte 10
Incremented byte 10
Original short 100
Incremented short 100
Original int 10
Incremented int 10
Original long 99999
Incremented long 99999
Original float 20.5
Incremented float  20.5
Original double 15.5
Incremented double 15.5





Program Analysis


In the output, you don't see the increment of any original value because -
• We are applying a post-increment operator on a primitive variable within Console.WriteLine() method.
• Hence, each original value of a variable is first read and printed right away.
• Next, this original value of variable is incremented, but it is not read or used to display in the output.





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Displaying incremented value after a post-increment operation




//C# Example of correctly displaying the incremented value after a post-increment operation

using System;

class A
{
public static void Main()
{
	//Local variables
	char ch = 'b';
	byte b = 20;
	short sh = 99;
	int i = 16;
	long l = 99999;
	float f = 20.5f;
	double d = 15.5;


	Console.WriteLine("Original character " + ch);
	ch++;
	Console.WriteLine("Incremented character " + ch);

	Console.WriteLine("Original byte " + b);
	b++;
	Console.WriteLine("Incremented byte " + b);

	Console.WriteLine("Original short " + sh);
	sh++;
	Console.WriteLine("Incremented short " + sh);

	Console.WriteLine("Original int " + i);
	i++;
	Console.WriteLine("Incremented int " + i);

	Console.WriteLine("Original long " + l);
	l++;
	Console.WriteLine("Incremented long " + l);

	Console.WriteLine("Original float " + f);
	f++;
	Console.WriteLine("Incremented float  " + f);

	Console.WriteLine("Original double " + d);
	d++;
	Console.WriteLine("Incremented double " + d);
}
}





Output-




Original character b
Incremented character c
Original byte 20
Incremented byte 21
Original short 99
Incremented short 100
Original int 16
Incremented int 17
Original long 99999
Incremented long 100000
Original float 20.5
Incremented float  21.5
Original double 15.5
Incremented double 16.5





Program Analysis



Now in the output, you see the incrementation of every original value because -
• Each original value of a variable is not read or used by any expression or a method.
• Hence, this original value is the incremented and its incremented value is printed in the output using Console.WriteLine() method in the next line.







Post and pre-increment operators in arithmetic expressions.




//C# Example of Post and pre-increment operators in arithmetic expressions.


using System;

class A
{
public static void Main()
{
	//Local variables 
	int a = 10, b=10, c=10, d=10;

	//Printing the values of local variables
	Console.WriteLine("a = " + a);
	Console.WriteLine("b = " + b);
	Console.WriteLine("c = " + c);
	Console.WriteLine("d = " + d);


	//first expression
	int result = a++ - 10;  	
	Console.WriteLine("Result of a++ - 10 = "+ result);
	Console.WriteLine("The incremented value of a = "+ a);

	//second expression
	result = ++b - 10; 		 
	Console.WriteLine("Result of ++b - 10 = "+ result);
	Console.WriteLine("The incremented value of b = "+ b);

	//third expression
	result = ++c - 10 + c++; 	 
	Console.WriteLine("Result of ++c - 10 + c++ = "+ result);
	Console.WriteLine("The incremented value of c = "+ c);

	//fourth expression
	result = d++ + ++d +10;		 
	Console.WriteLine("Result4 of d++ + ++d +10 = "+ result);
	Console.WriteLine("The incremented value of d = "+ d);
}
}


Output-

a = 10
b = 10
c = 10
d = 10
Result of a++ - 10 = 0
The incremented value of a = 11
Result of ++b - 10 = 1
The incremented value of b = 11
Result of ++c - 10 + c++ = 12
The incremented value of c = 12
Result4 of d++ + ++d +10 = 32
The incremented value of d = 12








Explaining the sequence of operations in each expression in our last code.

a++ - 10

1. Due to post-increment operator with a, its value 10 is first read to be subtracted by 10.
2. Next, the original value of a is incremented to 11.
3. Finally, result of 10-10 = 0, is passed to the result.

++b - 10

1. Due to pre-increment operator with b, its value 10 is first incremented to 11
2. Next, this incremented value of b, 11 is subtracted by 10
3. Finally, result of 11-10 = 1 , is passed ot the result.

++c - 10 + c++

1. Due to pre-increment operator with c, first its value 10 is incremented to 11
2. Next, this incremented value of c 11 is subtracted by 10, which results to 1.
3. In the next expression, due to post-increment operator with c, first the current value of a, 11 is read and added to 1 and then a is incremented to 12.
4. Finally, the result of 1+11 = 12, is passed to the result.

d++ + ++d +10

1. Due to post-increment operator with d, first its value 10 is read to be added to the next expression and then its value is incremented to 11.
2. In the next expression, due to pre-increment operator with d, its current value 11 is incremented to 12.
3. Next, due to d++ + ++d, leads to 10 + 12, which results to 22, which is added to 10.
4. Finally, the result of 22+10 = 32, is passed to the result.

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