3. If-else Ladder

if-else-if ladder helps user decide from among multiple options. if condition 1 is true then print the statement 1, otherwise check the condition 2 same as condtiton true print satement, otherwise go to next condition , all condition are false print the esle part.

syntax :
if (condition 1)
{
    //-----
    //-----
}
else if(condition 2)
{
    //----
    //----
}
else if(condition 3)
{
    //----
    //----
}
else if(condition 4)
{
    //----
    //----
}
else
{
  //----
}

Example 1 :

#include <iostream>
using namespace std;

int main() {
    int num;
    cout<<"Enter Number: ";
    cin>>num;

    if(num==1){
        cout<<"One";
    }
    else if(num==2){
        cout<<"Two";
    }
    else if(num==3){
        cout<<"Three";
    }
    else if(num==4){
        cout<<"Four";
    }
    else
    {
        cout<<"Not Matched :";
    }
     return 0;
}

Output :

Enter Number : 3
Three

Explanation :

Line 5 : declare variable num
Line 6 : Enter a number from user.
Line 7 : allocate memory for num variable.
Line 9 : if(num==1) check the condition condition true print statement otherwise goto next condition.
Line 12 : else if(num==2) check the condition condition true print statement otherwise goto next condition.
Line 15 : else if(num==3) check the condition condition true print statement otherwise goto next condition.
All condition are false then goto the esle part and print the else part .

Example 2 :

#include <iostream>
using namespace std;

int main() {
    int num;
    cout<<"Enter Number: ";
    cin>>num;

    if(num==1){
        cout<<"One";
    }
    else if(num==2){
        cout<<"Two";
    }
    else if(num==3){
        cout<<"Three";
    }
    else if(num==4){
        cout<<"Four";
    }
    else
    {
        cout<<"Not Matched...";
    }
     return 0;
}

Output :

Enter Number : 8
Not Matched...

Explanation :

Line 5 : declare variable num
Line 6 : Enter a number from user.
Line 7 : allocate memory for num variable.
Line 9 : if(num==1) check the condition, condition true print statement otherwise goto next condition.
Line 12 : else if(num==2) check the condition, condition true print statement otherwise goto next condition.
Line 15 : else if(num==3) check the condition, condition true print statement otherwise goto next condition.
All condition are false then goto the esle part and print the else part .

Example 3 : Boundry Condition

#include <iostream>
using namespace std;

int main() {
    int marks;

    cout<<"Enter Marks:";
    cin>>marks;

    if(marks>=70 && marks<=80){
        cout<<"Grade C";
    }
    else if(marks>=80 && marks<=90){
        cout<<"Grade B";
    }
    else if(marks>=90 && marks <=100){
        cout<<"Grade A";
    }
    else
    {
        cout<<"Invalid Number";
    }

    return 0;
}

Output :

Enter Marks : 90
A

Explanation :

Line 5 : declare variable marks
Line 6 : Enter marks from user.
Line 7 : allocate memory for marks variable.
Line 9 : if(marks>=70 && marks<=80) check condition, condition true print the Grade C otherwise got to next condition.
Line 12 : if(marks>=80 && marks<=90) check condition, condition true print the Grade B otherwise got to next condition.
Line 15 : if(marks>=90 && marks<=100) check condition, condition true print the Grade A otherwise got to else part.
All condition are false print the else part Invalid number.

Example 4 : Boundry Condition

#include <iostream>
using namespace std;

int main() {
    int marks;

    cout<<"Enter Marks:";
    cin>>marks;

    if(marks>=70 && marks<=80){
        cout<<"Grade C";
    }
    else if(marks>=80 && marks<=90){
        cout<<"Grade B";
    }
    else if(marks>=90 && marks <=100){
        cout<<"Grade A";
    }
    else
    {
        cout<<"Invalid Number";
    }

    return 0;
}

Output :

Enter Marks : 180
Invalid Number

Explanation :

Example 5 : Boundry Condition

#include <iostream>
using namespace std;

int main() {
    int marks;

    cout<<"Enter Marks:";
    cin>>marks;

    if(marks>=50 && marks<=60){
        cout<<"Grade E";
    }
    else if(marks>=60 && marks<=70){
        cout<<"Grade D";
    }
    else if(marks>=70 && marks<=80){
        cout<<"Grade c";
    }
    else if(marks>=80 && marks<=90){
        cout<<"Grade B";
    }
    else if(marks>=90 && marks <=100){
        cout<<"Grade A";
    }
    else
    {
        cout<<"Invalid Number";
    }

    return 0;
}

Output :

Enter Marks : 55
Grade E

Explanation :

Line 5 : declare variable marks
Line 6 : Enter marks from user.
Line 7 : allocate memory for marks variable.
Line 9 : if(marks>=50 && marks<=60) check condition, condition true print the Grade E otherwise got to next condition.
Line 9 : if(marks>=60 && marks<=70) check condition, condition true print the Grade D otherwise got to next condition.
Line 9 : if(marks>=70 && marks<=80) check condition, condition true print the Grade C otherwise got to next condition.
Line 12 : if(marks>=80 && marks<=90) check condition, condition true print the Grade B otherwise got to next condition.
Line 15 : if(marks>=90 && marks<=100) check condition, condition true print the Grade A otherwise got to else part.
All condition are false print the else part Invalid number.