They are used to compare some values and operate according to result.

The result can be true or false.

• If the condition is true, it operates everything in if statement.
• If the condition is false, it skips whole if statements and continue.

We can build conditional statements in two forms:

1-for multiple lines of operations;

if(condition){

statement 1;

statement 2;

…

}

2-for single line;

if (condition)

statement;

We can write paranthesis, but no need for this for single line.

*For building conditions, we use 2 types of operators:

1)Relational Operators

<, <=, >, >=

2)Equality Operators

==, !=

Ex; Write a program that allows the user to enter an integer. The program will print if the integer is positive or negative.

#include<stdio.h>

int main(){

int num;

printf("Enter an integer: ");

scanf("%d",&num);

if(num>0)

printf("%d is positive.",num);

if(num<0)

printf("%d is negative.",num);

return 0;

}

Output will be like that: (Bold ones are entered by the user)

Enter an integer: 78

78 is positive.

or if we enter negative number:

Enter an integer: -11

-11 is negative.

Ex; Write a program that allows the user to enter 2 integers. The program will print largest of them or they are equal.

#include<stdio.h>

int main(){

int num1,num2;

printf("Enter 2 integers: ");

scanf("%d%d",&num1,&num2);

if(num1>num2)

printf("%d is largest.",num1);

if(num2>num1)

printf("%d is largest.",num2);

if(num1==num2)

printf("They are equal to each other.");

return 0;

}

!!Pay Attention!!

“==” is equality operator.It’s used for comparing.

“=” is assignment operator. It’s used for assigning.

If we write

if (x=5){

…

}

this will be always true. It will make x’s value 5 and result will be always true. Don’t forget!

»Extra:If we write like below, it will print sth or not?

if ( 1 ){

printf(“Yes, this is true”);

}

Answer is in  the following lesson😉

?Answer of previous lesson’s extra:

int x,y;
x=5;
y=4;
float av= (x+y) / 2;

av=9/2;   // they have the same type, both of them are integer. Then result must be integer. Then;

av=4;

c ya !  🙂