while and do-while loop

2. While Loop

entry controlled loop
pre-tested
executes atleast zero times when condition is false .

syntax:
2. while(condition)
{// loop body start

} // loop body ends

Example 1 :

#include <iostream>
using namespace std;

int main() {

    int i=1;
    while(i<=5)
    {
      cout<<i<<"\n";
      i++;
    }
     return 0;
}

Output :

1
2
3
4
5

Explanation :

In a Line no 6 we declare one variable which name has i and store value 1, datatype is integer.
In a Line no 7 while(i<=5) while is keyword, check condition i<=5.
In a Line no 8 Start body of while loop .
In a Line no 9 print i variable using cout \n is used to new line.
In a Line no 10 increase value of i by one.
In a Line no 11 ends body of while loop .

Example 2 :

#include <iostream>
using namespace std;

int main() {

    int i=0;
    int n;

    cout<<"Enter n :"<<"\n";
    cin>>n;
    while(i<n)
    {
      cout<<i<<"\n";
      i++;
    }
     return 0;
}

Output :

0
2
3
.
.
.
9

Explanation :

In a Line no 6 we declare one variable which name has i and store value 1, datatype is integer.
In a Line no 7 we declare another variable which name has n.
In a Line no 9 Enter n : from user.
In a Line no 10 store value of n variable using cin object.
In a Line no 11 while(i<=5) while is keyword, check condition i<=5.
In a Line no 12 Start body of while loop .
In a Line no 13 print i variable using cout \n is used to new line.
In a Line no 14 increase value of i by one.
In a Line no 15 ends body of while loop .

Example 3 :

#include <iostream>
using namespace std;

int main() {

    int n;
    cout<<"Enter value of n: ";
    cin>>n;

    int i=1;
    while(i<=n)
    {
      cout<<i<<endl;
      i++;
    }
     return 0;
}

Output :

Enter value of n: 25
1
2
3
.
.
.
25

Explanation :

3. do-while loop :

exit controlled loop
post tested
it executes atleast once even if condition is false .

syntax:
3. do
{//  start

   [example]

} //  ends
while(condition);

Example 4 :

#include <iostream>
using namespace std;

int main() {

    int i=10;
    do
    {
      cout<<i<<"\n";
      i++;
    }
    while(i<=5);

    return 0;
}

Output :

10

Explanation :

In a Line no 6 we declare one variable which name has i and store value 10, datatype is integer.
In a Line no 7 do is a keyword.
In a Line no 8 Start body of do-while loop .
In a Line no 9 print i variable using cout \n is used to new line.
In a Line no 10 increase value of iby one.<br/> In aLine no 11ends body of while loop .<br/> In aLine no 12 while(i<=5) whileis keyword, check conditioni<=5`.

Example 5 :

#include <iostream>
using namespace std;

int main() {

    int i=10;
    do
    {
      cout<<i<<"\n";
      i++;
    }
    while(i<=10);

    return 0;
}

Output :

1
2
3
4
.
.
10

Explanation :

Example 6 : WAP to simulate video game menu
1---> New Game
2---> Resume
3---> Settings
4---> Exit

#include <iostream>
using namespace std;

int main() {

    int choice = -1;
    char ch= 'y';

    do
    {
      cout<<"####### Video Game #######"<< endl;
      cout<<"1 => New Game : "<<endl;
      cout<<"2 => Resume : "<<endl;
      cout<<"3 => Settings : "<<endl;
      cin>>choice;

      if(choice == 1)
      {
        cout<<"New game is starting...";
      }
      else if(choice == 2)
      {
        cout<<"Continue from where you left...";
      }
      else if(choice == 3)
      {
        cout<<"Select Settings...";
      }
      cout<<"\n\n Do you want to continue ? (y/n)";
      cin>>ch;
    }
    while(ch == 'y');

    return 0;
}

Output :

####### Video Game #######
1 => New Game
2 => Resume
3 => Settings
1
New game is starting...

Do you want to continue ? (y/n)y
####### Video Game #######
1 => New Game
2 => Resume
3 => Settings
2
Continue from where you left..."

Do you want to continue ? (y/n)y
####### Video Game #######
1 => New Game
2 => Resume
3 => Settings
3
Select Settings...

Do you want to continue ? (y/n)n

Difference between for, while, do-while loop :

for	while	do-while
syntax: for(initialization;condition;inc/dec)	syntax: while(condition){ //statements; }	syntax: do{ //statements; } while(condition);
Entry controlled loop	Entry controlled loop	Exist controlled loop
It executes atleast zero times, when condition is false	It executes atleast zero times, when condition is false	It executes atleast once times, when condition is false
The for loop is used for definite loops when the number of iteration is known	The while loop is used when the number of iteration is not known

while and do-while loop

2. While Loop​

3. do-while loop :​

2. While Loop

3. do-while loop :