Programming Problems Using Loop Constructs

Problem: Ten Even Integers

Write a JAVA program that will display the first ten even integers, beginning with 2, in ascending order.

Algorithm

Solution

                        
public class FirstTenEvenIntegers
{
	public static void main(String [] args)
	{
		//variable declaration
		int i;  //loop counter
		int endValue = 20; //set to last even value to be considered
		
		//loop from first even value to tenth even value, inclusive
		for(i = 2; i <= endValue; i++)
		{
			if(i % 2 == 0)	//test for an even value
				System.out.println(i);	//if even, display the value
		}
	}
}

Output

Problem: Multiples of 3

Write a JAVA program that will display all multiples of 3, from 3 to 300, inclusive.

Algorithm

Solution

                        
public class MultiplesOfThree
{
	public static void main(String [] args)
	{
		//variable declaration
		int i; 					//loop counter
		int endValue = 300;	//value to terminate loop
		
		//loop construct, iterates between start and end values, inclusive
		for(i = 3; i <= endValue; i++)
		{
			if(i % 3 == 0)		//test for multiple of three
				System.out.println(i);	//display the multiple of 3
				
		}
	}
}

Output

Problem: Multiples of 7

Write a JAVA program that will display all multiples of 7, from 7 to 700, inclusive.

Algorithm

Solution


public class MultiplesOfSeven
{
	public static void main(String [] args)
	{
		//variable declaration
		int i; 					//loop counter
		int endValue = 70;	//value to terminate loop
		
		//loop construct, iterates between start and end values, inclusive
		for(i = 7; i <= endValue; i++)
		{
			if(i % 7 == 0)		//test for multiple of three
				System.out.println(i);	//display the multiple of 3
				
		}
	}
}

Output

Problem: Even Integers From Two To Fifty

Write a JAVA program that will display the numbers between 2 and 50.

Algorithm

Solution


public class TwoToFifty
{
	public static void main(String[] args)
	{
		//variable declarations
		int startValue = 2;
		int endValue = 50;
		int i;  //loop control
		
		//process and output
		for(i = startValue; i <= endValue; i += 2)
			System.out.println(i);
	}
}

Output

Problem: Display Even Integers From Fifty To Two

Write a JAVA program that will display the numbers between 50 and 2, inclusive, in reverse order (beginning with fifty, and going to 2).

Algorithm

Solution


public class FiftyToTwo
{
	public static void main(String[] args)
	{
		//variable declaration
		int startValue = 50;
		int endValue = 2;
		int i;		//loop control
		
		//process and output
		for(i = startValue; i >= endValue; i -= 2)
			System.out.println(i);
	}
}

Output

Problem: Display Values From First User Input Value To Second User Input Value (ex. 1, ascending)

Prompt the user to input two values, a start value and an end value. The program is to display all the values from the start value to the end value, inclusive. (You may assume the start value entered by the user is less than or equal the end value).

Algorithm

Solution


import java.util.Scanner;

public class StartToEnd_ex1
{
	public static void main(String[] args)
	{
		//variable declaration
		int startVal = 0;
		int endVal = 0;
		Scanner kbd = new Scanner(System.in);
		int i;  //loop control
		
		//user prompt and data entry
		System.out.println("Please enter the starting value: ");
		startVal = kbd.nextInt();
		System.out.println("Please enter the ending value: ");
		endVal = kbd.nextInt();
		
		//program process and output
		System.out.println("The values from " + startVal + " to " +
				endVal + " are: ");
		for(i = startVal; i <= endVal; i++)
			System.out.println(i);
	}
}

Output

Please enter the starting value: 
20
Please enter the ending value: 
30
The values from 20 to 30 are: 
20
21
22
23
24
25
26
27
28
29
30

Problem: Display Values From First User Input Value To Second User Input Value (ex. 2, ascending, testing input values)

Prompt the user to input two values, a start value and an end value. The program is to display all the values from the start value to the end value, inclusive, in ascending order. (You SHOULD NOT assume that the start value entered by the user is less than or equal the end value).

Algorithm

Solution


import java.util.Scanner;

public class StartToEnd_ex2
{
	public static void main(String[]args)
	{
		//variable declaration
		int startVal = 0;
		int endVal = 0; 
		int tempStartVal = 0; //store untested user input value
		int tempEndVal = 0;	 //store untested user input value
		Scanner kbd = new Scanner(System.in);
		int i;  //loop control
		
		//user prompt and data entry
		System.out.println("Please enter the starting value: ");
		tempStartVal = kbd.nextInt();
		System.out.println("Please enter the ending value: ");
		tempEndVal = kbd.nextInt();
		
		//establish actual start value
		if(tempStartVal <= tempEndVal)
		{
			startVal = tempStartVal;
			endVal = tempEndVal;
		}
		else
		{
			startVal = tempEndVal; 	//place smaller value in startVal
			endVal = tempStartVal;	//place larger value in endVal
		}
		
		//program process and output
		System.out.println("The values from " + startVal + " to " +
				endVal + " are: ");
		for(i = startVal; i <= endVal; i++)
			System.out.println(i);
	}
}

Output

/*sample run 1*/
Please enter the starting value: 
10
Please enter the ending value: 
20
The values from 10 to 20 are: 
10
11
12
13
14
15
16
17
18
19
20

/*sample run 2*/
Please enter the starting value: 
20
Please enter the ending value: 
10
The values from 10 to 20 are: 
10
11
12
13
14
15
16
17
18
19
20

Problem: Display Values From First User Input Value To Second User Input Value (ex. 3, descending, testing input values)

Prompt the user to input two values, a start value and an end value. The program is to display all the values from the start value to the end value, inclusive, in descending order. (You SHOULD NOT assume that the start value entered by the user is less than or equal the end value).

Algorithm

Solution

                        
import java.util.Scanner;

public class StartToEnd_ex3
{
	public static void main(String[]args)
	{
		//variable declaration
		int highVal = 0;
		int lowVal = 0; 
		int tempStartVal = 0; //store untested user input value
		int tempEndVal = 0;	 //store untested user input value
		Scanner kbd = new Scanner(System.in);
		int i;  //loop control
		
		//user prompt and data entry
		System.out.println("Please enter the starting value: ");
		tempStartVal = kbd.nextInt();
		System.out.println("Please enter the ending value: ");
		tempEndVal = kbd.nextInt();
		
		//establish actual start value
		if(tempStartVal <= tempEndVal)
		{
			lowVal = tempStartVal;
			highVal = tempEndVal;
		}
		else
		{
			lowVal = tempEndVal; 	//place smaller value in startVal
			highVal = tempStartVal;	//place larger value in endVal
		}
		
		//program process and output
		System.out.println("The values from " + highVal + " to " +
				lowVal + " are: ");
		for(i = highVal; i >= lowVal; i--)
			System.out.println(i);
	}
}

Output


/*sample run 1*/
Please enter the starting value: 
10
Please enter the ending value: 
20
The values from 20 to 10 are: 
20
19
18
17
16
15
14
13
12
11
10

/*sample run 2*/
Please enter the starting value: 
20
Please enter the ending value: 
10
The values from 20 to 10 are: 
20
19
18
17
16
15
14
13
12
11
10

Problem: Display Multiples of 7 From First User Input Value To Second User Input Value (ascending, testing input values)

Prompt the user to input two values, a start value and an end value. The program is to display all multiples of 7 from the start value to the end value, inclusive, in ascending order. (You SHOULD NOT assume that the start value entered by the user is less than or equal the end value).

Algorithm

Solution

                        
import java.util.Scanner;

public class MultiplesOfSeven_WithLoop
{
	public static void main(String[]args)
	{
		//variable declaration
		int startVal = 0;
		int endVal = 0; 
		int tempStartVal = 0; //store untested user input value
		int tempEndVal = 0;	 //store untested user input value
		Scanner kbd = new Scanner(System.in);
		int i;  //loop control
		
		//user prompt and data entry
		System.out.println("Please enter the starting value: ");
		tempStartVal = kbd.nextInt();
		System.out.println("Please enter the ending value: ");
		tempEndVal = kbd.nextInt();
		
		//establish actual start value
		if(tempStartVal <= tempEndVal)
		{
			startVal = tempStartVal;
			endVal = tempEndVal;
		}
		else
		{
			startVal = tempEndVal; 	//place smaller value in startVal
			endVal = tempStartVal;	//place larger value in endVal
		}
		
		//program process and output
		System.out.println("The values from " + startVal + " to " +
				endVal + " are: ");
		for(i = startVal; i <= endVal; i++)
		{
			if(i % 7 == 0)
				System.out.println(i);
		}
	}
}

Output


/*sample input/output*/
Please enter the starting value: 
3
Please enter the ending value: 
99
The values from 3 to 99 are: 
7
14
21
28
35
42
49
56
63
70
77
84
91
98