Elements of programming-4

If statement.

It is a conditional statement. It conditionally executing a branch of statements .There are different types of if statement.

1.       simple if

2.       if-else

3.       if-else if-else

4.       switch statement.

Simple If statement:

A relational expression is checked. If the condition is true a block of coding will be executed.if  it returns false the block of coding will not get executed.

For example take the following c program

.

#include<stdio.h>

#include<conio.h>

void main()

{
int mark;

Clrscr();

printf(“enter your score”);

scanf(“%d”,&mark);

printf(“your score is %d”,mark);

if(mark>=90)

{

printf(“excellent”);

}

getch();

}

Program explanation:

The above program asks the score as input. It prints your  mark.if your mark>=90 then it additionally prints the output excellent.

If—else

In this case a relational expression is tested .if the result is true then a block of coding will be executed.if it returns false another block of coding will be executed.

#include<stdio.h>

#include<conio.h>

void main()

{
int mark;

Clrscr();

printf(“enter your score”);

scanf(“%d”,&mark);

printf(“your score is %d”,mark);

if(mark>=40)

{

printf(“pass”);

}

Else

{

Printf(“fail”);

}

getch();

}

Program explanation:

In the above c program mark is input. If it is greater than or equal  to 40 result is printed as false.

If the mark<40 else part will be executed  and printed as fail

                                                --------to be continued

                                                                muthu karthikeyan madurai

Elements of programming ----3

                             Muthu karthikeyan, Madurai

Operators:

 

Types of operator:

Arithmetic operator

Short hand assignment operator

Increment /decrement operator

Relational operators

Logic operator

Ternary operator

Arithmetic operator:

+, -, *, /, %

Plus, minus, multiplication, division         

First three are same as mathmetical  operations.

Fourth division operation is different. i.e if we divide a int by another int result is integer only

For example

13/5=2 is the result. Decimal portions were removed

If at least any one is float or double the result is float

For example:

13.0/5=2.6

13/5.0=2.6

13.0/5.0=2.6

o.k then what about % operator? do you think that it is percentage calculating operator?

No

It is called as modulus operator.

That is one integer is divided by another integer .it returns remainder value

Example : 13/5=3.

In c , c++   modulus  operations are performed on Integer type only. In advanced languages like java, c sharp,vb.net modulus operator is also can be used also on float and double.

Short hand Assignment operator:

a=a+5 can be also written as a+=5

a=a-5 can be also written as a-=5

It totally applied for all 5 types of arithmetic operator.

Increment/decrement operator:

++,--

a=10;

a++;

now a value will be eleven because ++ operator increases the value by one

also ++a will increment the values by one.

Next:

--

It is called as decrement operator.

a=10;

a--;

now q value be only nine. because decrement operator wil decrement by . one

and  --a  may also decrement the value by one.

But in order of execution ++a(pre increment operator )has order of process high in a mathematical expression is high. but a++ (post decrement operator).has low precedence. It also applies to decrement operator.

Relational operator:

It is used for comparing one value with other value. it returns only true or false value

<  less  than

<=less  than or equal to

> greater than

>=greater than or equal to

==equals to(note there are two = symbols

!=not equal to

Examples:

a=10;

b=5;

c=15;

d=10;

a>b   ----true

a>c-----false

a==d—true

a!=d---false

logical operators:

compare two or more relational expression. It also returns true or false value

&&,||,!

&&---(and) both side of relational expression must be true.

||-(or)at least one side of expression must be true.

!-it inverts the results (if the result is true  then the result is false and vice-versa

Examples:

(a>b)&&(a>c)

(a>b)||(a>c)

!(a>b)

Ternary operator:

Make a relational expression execution . if the expression returns true a value will be returned , if the result is false b value will be returned.

Syntax:

(a>b)?a : b;

a=10;b=5;

big=(a>b)?a:b;

First the comparison(a>b) returns true so a value(i.e 10) will be returned to big.

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