Difference between revisions of "C-and-C++/C2/Increment-And-Decrement-Operators/English"

Increment and decrement operators

++ eg. a++ which is a postfix increment operator.

++a which is a prefix increment operator.

- - eg. a- - is a postfix decrement operator.

- -a is a prefix decrement operator. We will also learn about Type casting.

Ubuntu 11.10 as the operating system and

gcc and g++ Compiler version 4.6.1 in Ubuntu.

a++ and ++a are equivalent to a = a + 1.

The -- operator decreases the existing value of the operand by one.

a-- and --a are equivalent to a = a - 1.

I have already made the program, so I'll explain the code.

Here, we have the code for increment and decrement operators in C.

int a=1;

This way we will be able to observe the changes in the value of a.

It will thus give us a better idea about the working of the operators.

printf("a's value is %d\n",

a++);

The output of this printf statement is 1.

The value won't change.

This is because the postfix operation occurs after the operand is evaluated.

If an operation is performed on a++, it is performed on the current value of a.

After that the value of a is incremented.

a);

a = 1;

printf(“a's value is now %d\n”,

++a);

This printf statement prints 2 on the screen.

This is because a prefix operation occurs before the operand is evaluated.

So the value of a is first incremented by 1 and then it is printed.

We again print a's value to see that there are no further changes.

*/

I will comment out the following lines.

Type /*

*/

I have saved my file as incrdecr.c

gcc incrdecr.c -o incr

Type

./incr

gcc space incrdecr.c space -o space incr Press Enter

To execute the code, type

./incr Press Enter

Output a's value is now 1

a's value is now 2

a's value is 2

a's value is now 2

This is the output when you print a++

This is the output when you print ++a.

We can see that the result is as discussed before.

I will now explain the postfix and prefix decrement operators.

Remove the multilinecomments from here and here.

a=1

printf("a's value is %d\n”,

a--);

A's value will be decremented after a-- is evaluated as its a postfix expression.

printf("a's value is now %d\n”, a);

A's value is now decemented by 1.

printf("a's value is now %d\n”, --a);

Output of this printf statement will be 0.

As it is a prefix operation.

The prefix operation occurs before the operand is evaluated.

No further changes are being made to a's value.

And close the ending curly bracket

Switch back to the terminal.

To compile type the following on the terminal;

gcc space incrdecr.c space -o space incr Press Enter

To execute type,

./incr Press Enter

a's value is now 1

a's value is now 0

a's value is now 0

a's value is now 0

This is the output when you print a--

This is the output when you print --a

So, now we see how the increment and decrement operators work.

I can make a few changes to the above C code.

#include <iostream>

using namespace std;

int main()

{

int a=1;

cout <<"a's value is " <<a++ <<"\n";

cout <<"a's value is now " <<a <<"\n";

a=1;

cout <<"a's value is now " <<++a <<"\n";

cout <<"a's value is now " <<a <<"\n";

a=1;

cout <<"a's value is now " <<a-- <<"\n";

cout <<"a's value is now " <<a <<"\n";

a=1;

return 0;

}

#include<iostream>

using namespace std;

cout

We have the using namespace statement also.

Also, note that the output statement in C++ is cout.

So, apart from these differences, the two codes are very similar.

The file is saved with an extension .cpp

g++ incrdecr.cpp -o incr

./ incr

Open the terminal and type

g++ space incrdecr.cpp space -o incr Press Enter

To execute

Type

./incr

Press Enter

a's value is 1

a's value is now 2

a's value is now 2

a's value is now 2

a's value is now 1

a's value is now 0

a's value is now 0

a's value is now 0

So, we see the output is identical to the C program.

It is implemented the same way in both C and C++.

Typecasting is a used to make a variable of one type, act like another type.

Highlight

(float)

Highlight

(int) a

This cast is put in front of the variable you want to cast.

This typecast is valid for one single operation only.

Now a will behave as a float variable for a single operation.

I shall now explain the code.

int a,b;

float c;

a=5;

b=2;

b is assigned the value of 2.

We will perform operations on a and b.

c=a/b;

The result of division is stored in c.

printf(“Value of c is %.2f\n”, c);

The result displayed will be 2.00 against the expected result of 2.50.

The fractional part has been truncated as both the operands a and b are integers.

To perform real division one of the operands will have to be type cast to float.

c=(float)a/b;

c now holds the value of real division.

printf(“Value of c is %.2f\n”, c);

The answer is 2.50 as expected.

return 0;

}

and the close the ending curly bracket.

Save the file with .c extension.

I have saved my file as typecast.c.

gcc typecast.c -o type

./type

To compile, type

gcc space typecast.c space -o space type Press Enter

to execute, type

./type Press Enter

Value of c is 2.00

Value of c is 2.50

looking at the two values we see the effects of typecasting.

In this tutorial we learnt,

How to use the increment and decrement operators. We learnt about the forms

Postfix and Prefix

Also we learnt about typecasting and how it is used.

Write a program to solve the following expression,

(a\b) + (c\d)

The values of a, b, c and d are taken as input from the user.

Use typecasting to perform real division.

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