Conditional statements help you to make a decision based on certain conditions. These conditions are specified by a set of conditional statements having boolean expressions which are evaluated to a boolean value true or false. There are following types of conditional statements in C.
1. If statement
2. If-Else statement
3. Nested If-else statement
4. If-Else If ladder
5. Switch statement
If statement
The single if statement in C language is used to execute the code if a condition is true. It is also called one-way selection statement.
Syntax
if(expression){ //code to be executed}
How “if” statement works..
· If the expression is evaluated to nonzero (true) then if block statement(s) are executed.
· If the expression is evaluated to zero (false) then Control passes to the next statement following it.
Note
“Expression must be scalar type” i.e evaluated to a single value.
if Statement Example
#include<stdio.h>#include<conio.h>void main(){int num=0;printf("enter the number");scanf("%d",&num);if(n%2==0){printf("%d number in even",num);}getch();}If-else statement
The if-else statement in C language is used to execute the code if condition is true or false. It is also called two-way selection statement.
Syntax
if(expression){ //Statements}else{ //Statements}
How “if..else” statement works..
· If the expression is evaluated to nonzero (true) then if block statement(s) are executed.
· If the expression is evaluated to zero (false) then else block statement(s) are executed.
if..else Statement Example
#include<stdio.h>#include<conio.h>void main(){int num=0;printf("enter the number");scanf("%d",&num);if(n%2==0){printf("%d number in even", num);}else{printf("%d number in odd",num);}getch();}Nested If-else statement
The nested if…else statement is used when a program requires more than one test expression. It is also called a multi-way selection statement. When a series of the decision are involved in a statement, we use if else statement in nested form.
Syntax
if( expression ){ if( expression1 ) { statement-block1; } else { statement-block 2; }}else{ statement-block 3;}Example
#include<stdio.h>#include<conio.h>void main( ){ int a,b,c; clrscr(); printf("Please Enter 3 number"); scanf("%d%d%d",&a,&b,&c); if(a>b) { if(a>c) { printf("a is greatest"); } else { printf("c is greatest"); } } else { if(b>c) { printf("b is greatest"); } else { printf("c is greatest"); } }getch();} If..else If ladder
The if-else-if statement is used to execute one code from multiple conditions. It is also called multipath decision statement. It is a chain of if..else statements in which each if statement is associated with else if statement and last would be an else statement.
Syntax
if(condition1){ //statements} else if(condition2){ //statements}else if(condition3){ //statements}else{ //statements}
If..else If ladder Example
#include<stdio.h>#include<conio.h>void main( ){ int a; printf("enter a number"); scanf("%d",&a); if( a%5==0 && a%8==0) { printf("divisible by both 5 and 8"); } else if( a%8==0 ) { printf("divisible by 8"); } else if(a%5==0) { printf("divisible by 5"); } else { printf("divisible by none"); }getch();}Switch Statement
switch statement acts as a substitute for a long if-else-if ladder that is used to test a list of cases. A switch statement contains one or more case labels which are tested against the switch expression. When the expression match to a case then the associated statements with that case would be executed.
Syntax
Switch (expression){ case value1: //Statements break; case value 2: //Statements break; case value 3: //Statements case value n: //Statements break; Default: //Statements} 
switch statement Example
#include<stdio.h>#include<conio.h>void main( ){ char grade = 'B'; if (grade == 'A') { printf("Excellent!"); } else if (grade == 'B') { printf("Well done"); } else if (grade == 'D') { printf("You passed"); } else if (grade == 'F') { printf("Better try again"); } else { printf("You Failed!"); } }getch();}Read More Articles Related to C Programming Language
Note
· The switch statement must be an integral type.
· Case labels must be constants.
· Case labels must be unique.
· Case labels must end with a colon.
· The break statement transfers the control out of switch statement.
· The break statement is optional.
