If-else and switch statement in C

 If-else and switch statement in C

Here we will discuss

• If-else statement
• Relational Operator
• Logical operator
• Ternary Statement
• Switch statement

Sometimes we have to program a code with conditions.

Decision-making instruction is as follows:

1. an if-else statement
2. Switch statement

If-else Statement

If else statement is used to give conditions for programming.

Syntax of an if-else statement is:

if( /*condition*/)

{

    /*code*/

}

else

{

    /*code*/

}

 For example:-

Write a code to state whether a number is odd or even.

Answer: To write this code we will use an if-else statement and modular operator.

#include<stdio.h>

int main(){

int a;

printf("Enter a number\n");

scanf("%d",&a);

if (a%2==0){

    printf("%d is even",a);

}

else

{

    printf("%d is odd",a);

}

return 0;

}

Its output will be

The output of the program tells us whether a number is odd or even

 Operators used for Decision making instructions are as follows:

1. Relational Operator
2. Logical Operator

Relational Operator

The relational operator is used to check the condition whether it is true or false in an if-else statement.

Expression	meaning
==	Equal to
!=	Not equal to
>	Greater than
<	Less than
>=	Greater than and equal to
<=	Less than and equal to

 

Note: = is an assignment operator where as == is used to check equality

Example: sum=a+b;

                  If(sum==4){

                                Printf(“Sum of two number is 4”);

                    }

Logical Operator

A logical operator is used to assigning more conditions in an if-else statement.

There are three logical operators

Expression	Name
&&	AND
||	OR
!	NOT

 

&& operator: AND operator states that when both conditions will be true then only statement executes.

|| operator: OR operator states that when anyone condition will be true or both conditions will true then the statement should execute.

! operator: NOT operator states when both conditions will be false then the only statement executes.

 

If we have to execute multiple statements with the condition then we can use if-else if-else statement.

Syntax for using if-else if-else statement is as follows:

If(/*condition*/)

{

               /*statement*/

}

else if(/*condition*/)

{

               /*statement*/

}

else (/*condition*/)

{

               /*statement*/

}

 

For example

Write a program to show whether a number is divisible with 2, 3, and 4.

Answer :   

#include<stdio.h>

int main(){

    int a;

    printf("Enter the value :\n");

    scanf("%d",&a);

    if(a%2==0){

        printf("%d is divisible by 2",a);

    }

    else if (a%3==0)

    {

        printf("%d is divisible by 3",a);

    }

    else

    {

        printf("%d is not divisible by 2 and 3",a);

    }

    

return 0;

}

Its Output is

The output of if-else if statements example

Note: It is not necessary to put else statement. If-else statement works without else statement too.

Now we have studied all types of operators. So, the hierarchy of operator in C is as follows:

Priority	Operator
First	!
Second	*, /, %
Third	+, -
Forth	<, >, <=, >=
Fifth	==, !=
Sixth	&&
Seventh	||
eighth	=

 
Conditional operator or Ternary operator:

? and : are the conditional operator which is also sometimes known as the ternary operator.

Syntax of the ternary operator is as follows:

(expression 1? expression 2: expression 3)

For example:

Write a program to show which one is greater between two number?

#include <stdio.h>

int main()

{

    int a, b, c;

    printf("Enter the value of a : \n");

    scanf("%d", &a);

    printf("Enter the value of b : \n");

    scanf("%d", &b);

    c= (a<b) ? a:b;

    printf("%d is greater",c);

    return 0;

}

Its output is

The output of the Conditional statement

 

 Switch Statement

Switch case-control instruction is used to give the number of alternatives or choice to make a decision. It gives us more than one alternative to choose in which method we have to work.

Syntax of Switch-case statement is as follow:

    switch (expression)

    {

    case /* constant-expression */:

        /* code */

        break;

        case /* constant-expression */:

        /* code */

        break;

    default:

        break;

    }

Note: 

• /*constant-expression*/: Here we write the constant which we choose in execution. 
• /*code*/: Here we write valid which execute.
• break: break statement is used to terminate the process.

For example:

Write a program to make a calculator using a switch-case statement?

#include<stdio.h>

int main(){

char operator;

float a,b;

printf("Operator is \n ");

scanf("%c",&operator);

printf("Enter value of a \n");

scanf("%f",&a);

printf("Enter value of b\n ");

scanf("%f",&b);

switch(operator){

    case '+':

    printf("%f+%f=%f",a,b,a+b);

    break;

    case '-':

    printf("%f-%f=%f",a,b,a-b);

    break;

    case '*':

    printf("%f*%f=%f",a,b,a*b);

    break;

    case '/':

    printf("%f/%f=%f",a,b,a/b);

    break;

}

return 0;

}

Its output is

The output of the switch-calculator