# while-loop

##### EXERCISE

- Programming in C++
- store a full length of name in C++
- find out in given number, even or odd in C++
- using formula in C++
- arithmetical progression using C++
- found a given number is positive or negative in C++
- find a largest number in any three given number
- for-loop
- while-loop
- do-while loop
- add array elements total in C++
- Add different array element with each other
- structure programs in C++
- function exercise
- file handling programs in C++

In this page we create two program using do-while loop,

## Print a fibonacci series using while loop

before starting program, what is fibonacci series?

In Fibonacci series, the first number and the second number are total, is the third number.

`first number + second number = third number`

such as,

Here is the program,

```
#include<iostream.h>
#include<conio.h>
void main()
{
int first=0,second=1,next;
int num;
clrscr();
cout<<"Enter the number of terms in series:"; cin>>num;
cout<<first<<"\t"<<second;
int i=3;
while(i<=num)
{
next=first+second;
cout<<"\t"<<next;
first=second; // now first number is second
second=next; // and second number is next
i++;
}
getch();
}
```

**OUTPUT:-**
Enter the number of terms in series: 8
0 1 1 2 3 5 8 13

**explanation:**

In the program, we have declared the following variables.

`int num, first,second,next;`

In which variable first and wearable seconds have been initialized and variable numbers have been used to store user input.

Suppose user input is 8

`num =8;`

First of all we have printed the value of variable first and wearable seconds.

After this the loop starts.

We have assigned the value 3 to the variable i here because we have already printed in two terms(variable first and second) of the series.

in the program loop will be execute like below,

**in first first = 0 second = 1 i =3**

```
while(3<=8) {
next = first+second; //0+1;
cout<<next; // 1
first = second; //1
second = next//1
3++; // 4
}
```

**now first =1 , second =1 i =4**

```
while(4<=8) {
next = first+second;//1+1
cout<<next;// 2
first = second; // 1
second = next//2
4++; // 5
}
```

**now first =1 second =2 i =5**

```
while(5<=8) {
next = first+second;//1+2
cout<<next;// 3
first = second; // 2
second = next//3
5++; // 6
}
```

**now first = 2 second =3 i =6**

```
while(6<=8) {
next = first+second;//2+3
cout<<next;// 5
first = second; // 3
second = next//5
6++; // 7
}
```

**now first = 3 second =3 i =7**

```
while(7<=8) {
next = first+second;//3+5
cout<<next;// 8
first = second; // 5
second = next//8
7++; // 8
}
```

**now first = 5 second = 8 i =8** and in last execution 13 will be print as above manner

in the value of variable i increase by 1 so its become 9 so condition will be such as,

`while( 9<=8)`

which becoming false so loop will be terminat and we get the following output,

`0 1 1 2 3 5 8 13`

## Generate a large form of table of given number using while and for loop

#include #include void main() { clrscr(); int first,last; cout<<"Enter first number: "; cin>>first; cout<<"Enter last number: "; cin>>last; int i =1; while(i<=10) { for(int j=f; j<=l;j++) { cout<<i*j<<"\t"; } cout<<endl; i++; } getch(); }

OUTPUT:-Enter first number: 5 Enter last number: 15 5 6 7 8 9 10 11 12 13 14 15 10 12 14 16 18 20 22 24 26 28 30 15 18 21 24 27 30 33 36 39 42 45 20 24 28 32 36 40 44 48 52 56 60 25 30 35 40 45 50 55 60 65 70 75 30 36 42 48 54 60 66 72 78 84 90 35 42 49 56 63 70 77 84 91 98 105 40 48 56 64 72 80 88 96 104 112 120 45 54 63 72 81 90 99 108 117 126 135 50 60 70 80 90 100 110 120 130 140 150