example1.c
-----------------------------------------------
#include <iostream>

using namespace std;

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

===============================================

example2.c
-----------------------------------------------
#include <iostream>

using namespace std;

int main(){
    int number;
    cout << "Enter a number: ";
    cin >> number;
    
    while(number > 0){
        cout << number << "\t";
        number--;
    }
    cout << endl;

}

================================================

example3.c
------------------------------------------------
#include <iostream>

using namespace std;

int main(){
	int factor, number;
	cout << "Enter a number: ";
	cin >> number;
	
	factor = 2;         
	while(number%factor !=0)
     		factor++;
	cout << "The smallest factor is " << factor << endl;


}

================================================

example4.c
------------------------------------------------
#include <iostream>

using namespace std;

int main(){
    int x, sum=0;
    cout << "Enter data (-1 to stop) : ";
    cin >> x;
    while(x != -1){
        sum = sum + x;
        cout << "Enter data (-1 to stop) : ";
        cin >> x;
    }
    cout << "Sum = " << sum << endl;

}

================================================     

example5.c
------------------------------------------------
#include <iostream>

using namespace std;

int main(){
    int n;
    do{
        cout << "Enter a positive value: ";
        cin >> n;
    }while(n<0);
    cout << "The number you entered is " << n << endl;

}

================================================

example6.c
------------------------------------------------
#include <iostream>

using namespace std;

int main(){
    int n;
    do{
        cout << "Enter the mark = ";
        cin >> n;
    }while(n<0||n>100);
    cout << "Mark = " << n << endl;


}

================================================

example7.c
------------------------------------------------
#include <iostream>

using namespace std;

int main(){

    char g, temp;
    do{
        cout << "Enter your gender (f=female/m=male): ";
        cin >> g;
    }while(g!='f'&&g!='m');
    cout << "Gender = " << g << endl;

}

================================================

example8.c
------------------------------------------------
#include <iostream>

using namespace std;

int main(){

    int x;
    float reciprocal;        
    do{
        cout << "Enter a number: ";
        cin >> x;
        if(x<=0)   
            cout << "Error." << endl;
    }while(x<=0);
    reciprocal = 1.0/x;
    cout << "Reciprocal = " << reciprocal << endl;

}

================================================