Revision as of 12:41, 6 April 2010

Problem

Write a method which accepts an array of integers and an integer value x. The method will perform a linear search of the array. A counter should be incremented each time the value x occurs in the array. The method should return an integer value indicating the number of times the value x occurs in the array.

...by students

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Solution

Initialize the variables we will need. We will need an integer to count the number of times x occurs in the array, and an integer to iterate through the array.

int count = 0;
int i;

Before trying to iterate through the array, make sure it is properly initialized. If the array is null, we cannot search the array, so we will return 0.

if (array != null)

Iterate through each element of the array. On each iteration, compare the current element with the value of x. If the values are equal, increment the counter variable.

for (i = 0; i < array.length; i++){
    if (array [i] == x)
        ++counter;
} // for

Return the number of times element x occured in the array.

return count;

Code

Solution Code

public class LinearSearchCountX
{

	public static void main(String [] args)
	{
		int [] array = {1,2,3,3,4,5,6,7};  // the array to search
		int x = 3;                         // the element we are counting
		int count = 0;                     // number of times x occurs in the array

		// count element x
		count = countElementX (array, x);

		// provide some nice output
		if (count == 0)
			System.out.println("The element " + x + " does not occurs in the array");
		else if (count == 1)
			System.out.println ("The element " + x + " occurs in the array one time");
		else
			System.out.println ("The element " + x + " occurs in the array " + count + " times");

	} // main

	private static int countElementX (int [] array, int x)
	{
		int count = 0;	// count the number of times x occurs
		int i;			// iterate through the array

		// check for null before trying to iterate through it
		if (array != null)
		{
			// iterate through all the elements in the array
			for (i = 0; i < array.length; i++)
			{
				// compare the current element with x
				if (array [i] == x)
				{
					// increment the count
					++count;
				} // if
			} // for
		} // if

		return count;
	} // countElement
} // Arrays

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Difference between revisions of "Count Element x Using Linear Search"

Revision as of 12:41, 6 April 2010

Problem

...by students

Solution

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@@ Line 69: / Line 69: @@
 </pre>
-Before trying to iterate through the array, make sure it is properly initialized.  If the array is null, we don't have an array to search so we will return 0.
+Before trying to iterate through the array, make sure it is properly initialized.  If the array is null, we cannot search the array, so we will return 0.
 <pre>
 if (array != null)