If Statements and its types
C provides two styles of flow control:
• Branching
• Looping
Branching:
- Branching is deciding what actions to take and looping is deciding how many times to take a certain action.
- Branching is so called because the program chooses to follow one branch or another.
- In decision control statements (C if else and nested if), group of statements are executed when condition is true. If condition is false, then else part statements are executed.
- There are 3 types of decision making control statements in C language. They are,
Branching:
- Branching is deciding what actions to take and looping is deciding how many times to take a certain action.
- Branching is so called because the program chooses to follow one branch or another.
- In decision control statements (C if else and nested if), group of statements are executed when condition is true. If condition is false, then else part statements are executed.
- There are 3 types of decision making control statements in C language. They are,
- if statements
- if else statements
- nested if statements
If Statement
Let us clarify some concepts of “If”, “else” and “nested if” decision control statements
- Syntax for each C decision control statements are given in below table with description.
| Decision control statements | Syntax | Description |
| if | if (condition) { Statements; } | In these type of statements, if condition is true, then respective block of code is executed. |
| if…else | if (condition) { Statement1; Statement2; } else { Statement3; Statement4; } | In these type of statements, group of statements are executed when condition is true. If condition is false, then else part statements are executed. |
| nested if | if (condition1) { Statement1; } else_if(condition2) { Statement2; } else Statement 3; | If condition 1 is false, then condition 2 is checked and statements are executed if it is true. If condition 2 also gets failure, then else part is executed. |
1. if statement
- This is the most simple form of the branching statements.
NOTE: Expression will be assumed to be true if its evaluated values is non-zero.
if statements take the following form:
Example program for if statement in C:
In “if” control statement, respective block of code is executed when condition is true.
#include<stdio.h>
#include<conio.h>
void main( )
{
int a;
printf("n Enter a number:");
scanf("%d", &a);
if(a>0)
{
printf( "n The number %d is positive.",a);
getch();
}
More Example:
#include<stdio.h> #include<conio.h> void main()
{
int m=40,n=40;
if (m == n)
{
printf("m and n are equal");
}
}
Output:
| m and n are equal |
- The single if statement in C language is used to execute the code if condition is true. The syntax of if statement is given below.
Let's see a simple example of c language if statement.
#include<stdio.h>
#include<conio.h>
void main(){
int number=0;
clrscr();
printf("enter a number:");
scanf("%d",&number);
if(number%2==0){
printf("%d is even number",number);
}
getch();
}
Output
enter a number:4
4 is even number
enter a number:5
Nested-if statement
- In “nested if” control statement, if condition 1 is false, then condition 2 is checked and statements are executed if it is true.
- If condition 2 also gets failure, then else part is executed.
Example program for nested if statement in C:
#include <stdio.h>
int main()
{
int m=40,n=20;
if (m>n) {
printf("m is greater than n");
}
else if(m<n) {
printf("m is less than n");
}
else {
printf("m is equal to n");
}
}
Output:
m is greater than n
