Multiplication Table (10 x 10)

Thursday, September 12, 2013 1 Comments A+ a-

C++ program for Multiplication table (10 x 10)


Problem:
Write a multiplication table ( 10 x 10)
The following program shows a 10 x 10 multiplication table.
It uses the escape sequence for horizontal tab (\t) to properly align the table.

/*
Multiplication Table (10 * 10)
*/
#include <iostream>

using namespace std;

int main(void)
{
 int x,y;
 char waitInput;

 for(x=1; x<=10; x++)
 {
  for(y=1; y<=10; y++)
  {
   //use horizontal tab (\t) to align properly
   cout << "\t" << (x*y);
  }

  //newlines
  cout<<endl<<endl;
 }

 cin>>waitInput;
 return 0;
}

Reverse The Number

Wednesday, September 11, 2013 6 Comments A+ a-

C++ program to reverse the number


Problem:
Write a C++ program which ask for a number and reverse its digits.
Ex. Number = 1234 , the answer will be 4321
In order to reverse the number, we have to get the every digit starting from the rightmost or the last digit. In the above example it is number 4, then next is 3, then 2 until 1.

Steps to extract each digit and construct the reversed value of the number:

1) Extract the last digit through the use of modulus operator (%) to get the remainder when the a number is divided by 10.
2) Add the extracted digit to a reversed number variable (ex. reversedNum) which will be constructed. The variable should be initialized to 0 and must be multiplied with 10 before the extracted digit is added.
3) After the last digit is extracted, divide the number with 10 to eliminate the extracted digit and start again to Step 1. The cycle continues until there is number is already 0.

The following program shows how to reverse the digits of a number.

/*
Reverse the number
*/
#include <iostream>

using namespace std;

int main(void)
{
 long number, remainder, reverseNumber = 0;
 char hang;

 cout<< "Enter the number: ";
 cin>>number;
 
 while(number)
 {
  //extract the last digit from the number
  remainder = number % 10;  

  //build the reverseNumber digit by digit
  reverseNumber = (reverseNumber * 10) + remainder;

  //exclude the last digit from the number
  //ready for the next evaluation
  number = number / 10;    
 }

 cout<< "Reversed number = " << reverseNumber <<endl;
 
 //to let console stay
 cin>>hang;
 
 return 0;
}
Output of the program:

//Sample 1

Enter the number: 1235
Reversed number = 5321

//Sample 2

Enter the number: 1023
Reversed number = 3201

//Sample 3

Enter the number: 5007
Reversed number = 7005

//*Sample 4

Enter the number: 012
Reversed number = 21

//*Sample 5

Enter the number: 210
Reversed number = 12

*Note that for inputs having 0 in the beginning and in the end, 0 will not be include in the output, See below:
Input = 012        Output = 21 ( 012 is considered as 12 because the 0 is not significant)
Input = 210        Output = 12 ( instead of 012, 0 is not significant in the answer)

Check If A Number Is A Prime Number

Tuesday, September 10, 2013 5 Comments A+ a-


C++ program to check if a number is a prime number


Problem:
Write a C++ program which checks if a number is a prime number or not?
A prime number is any natural number greater than 1 with no other positive factors other than 1 and itself. 

Let's take 5 as an example:
1 and 5 (the number itself) can evenly divide 5 so they are factors of 5.
2, 3, 4 are cannot evenly divide 5 so they are not factors of 5.
Therefore, 5 is a Prime Number.
The program below shows a number is asked and it is evaluated if a prime number or not.

Prime Numbers Between 1-1000

Monday, September 09, 2013 5 Comments A+ a-

C++ program to find prime numbers between 1 to 1000


Problem:
Write a C++ program which prints all the prime numbers from 1-1000. 

Prime numbers are numbers greater than 1 and which has 1 and the number itself as positive factors or divisors. It doesn't have a positive factor or divisors other than 1 and the number itself.

Let's take 5 for example:
1 and 5 (the number itself) can evenly divide 5 so they are factors of 5.
2, 3, 4 are cannot evenly divide 5 so they are not factors of 5.
Therefore, 5 is a Prime Number.

This is a program which shows the Prime Numbers from 1-1000.

Fibonacci Numbers using Recursion

Sunday, September 08, 2013 4 Comments A+ a-

C++ program - Fibonacci numbers using recursion


Problem:
Write a C++ program which prints the Fibonacci sequence or the Fibonacci numbers.
Fibonacci sequence is named after Leonardo Fibonacci. Fibonacci numbers starts with the first two numbers 0 and 1, and each subsequent numbers takes as the sum of its previous two numbers.

Ex. 0, 1, 1, 2, 3, 5
The first two numbers in the sequence are 0 and 1.
The 3rd number which is 1 is the sum of its previous two numbers - 0 and 1.
The 4th number which is 2 is the sum of its previous two numbers  - 1 and 1.
So on and so forth...
In mathematical equation, Fibonacci sequence can be represented as:

Fn = F(n-1) + F(n-2) where F0 = 0, F1 = 1

The following program shows the Fibonacci sequence using recursion.