Difference between revisions of "Equating Two Arrays"
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{{1010PrAD|ProblemName=Equating Two Arrays | {{1010PrAD|ProblemName=Equating Two Arrays | ||
| − | |Problem= This problem | + | |Problem= This problem involves checking if two hard coded arrays are equal. You should use two int arrays to equate. Even though your arrays are hard coded into your program, you should not assume to know the length of the arrays. In other words use: {{CodeBlock|Code=array.length}} Remember that your arrays start indexing at 0 and that you should watch out for loops indexing arrays out of bounds. These are the most common pitfalls with a problem like this. Try to structure your code so that your loop is only comparing to the length of one of the arrays and not both of them. Print out whether your arrays are equal or not to the console using: {{CodeBlock|Code=System.out.println();}} |
|SideSectionTitle=Introducing Arrays | |SideSectionTitle=Introducing Arrays | ||
|SideSection=[[Image:Wiki_array01.jpg|center]]<BR> | |SideSection=[[Image:Wiki_array01.jpg|center]]<BR> | ||
| − | |Solution=The Solution to this problem is to use a boolean value to say whether or not the arrays are equal. Assume that they are equal at first and initialize | + | |Solution=The Solution to this problem is to use a boolean value to say whether or not the arrays are equal. Assume that they are equal at first and initialize the boolean variable to ''true''. Once you have your two int arrays set up in the code the next part is to start finding a solution to the problem. The best way is to start by checking the two lengths of the arrays by doing this: |
| − | + | {{CodeBlock|Code= | |
if (array1.length == array2.length) | if (array1.length == array2.length) | ||
{ | { | ||
} | } | ||
else | else | ||
| − | + | equal = false; | |
| − | + | }} | |
| − | This is done because if the two arrays are not equal in length then | + | This is done because if the two arrays are not equal in length then they are obviously not equal. By checking this simple property first, you save yourself from having to check the length of two arrays when iterating through them. The next step is to actually compare the values of the two arrays together by iterating through them with a loop. The best kind of loop for this task would be a for loop. |
| − | + | {{CodeBlock|Code= | |
for (int i = 0; i < array1.length; i++) | for (int i = 0; i < array1.length; i++) | ||
{ | { | ||
if (array1[i] != array2[i]) | if (array1[i] != array2[i]) | ||
| − | + | equal = false; | |
} | } | ||
| − | + | }} | |
| − | + | Because we already checked that the lengths were the same, we can use either value for both array lengths. It doesn't matter which one you use. By inserting this for loop into our if statement from before, we have a simple algorithm to test if two arrays are equal or not. You do another if statement at the bottom to print out your result based on the boolean variable ''equal''. | |
|SolutionCode= | |SolutionCode= | ||
| − | |||
public class ArrayEquate | public class ArrayEquate | ||
{ | { | ||
| Line 33: | Line 32: | ||
boolean equal = true; //boolean to say whether the arrays are equal or not. | boolean equal = true; //boolean to say whether the arrays are equal or not. | ||
| − | //Check to see if the arrays are equal in | + | //Check to see if the arrays are equal in length, if they are not the arrays can not be equal. |
if (array1.length == array2.length) | if (array1.length == array2.length) | ||
{ | { | ||
| Line 54: | Line 53: | ||
} | } | ||
} | } | ||
| − | |||
}} | }} | ||
Latest revision as of 15:52, 4 December 2011
Back to the Program-A-Day homepage
ProblemThis problem involves checking if two hard coded arrays are equal. You should use two int arrays to equate. Even though your arrays are hard coded into your program, you should not assume to know the length of the arrays. In other words use:array.lengthRemember that your arrays start indexing at 0 and that you should watch out for loops indexing arrays out of bounds. These are the most common pitfalls with a problem like this. Try to structure your code so that your loop is only comparing to the length of one of the arrays and not both of them. Print out whether your arrays are equal or not to the console using: System.out.println(); |
Introducing Arrays | |
|---|---|---|
SolutionThe Solution to this problem is to use a boolean value to say whether or not the arrays are equal. Assume that they are equal at first and initialize the boolean variable to true. Once you have your two int arrays set up in the code the next part is to start finding a solution to the problem. The best way is to start by checking the two lengths of the arrays by doing this: if (array1.length == array2.length)
{
}
else
equal = false;
This is done because if the two arrays are not equal in length then they are obviously not equal. By checking this simple property first, you save yourself from having to check the length of two arrays when iterating through them. The next step is to actually compare the values of the two arrays together by iterating through them with a loop. The best kind of loop for this task would be a for loop. for (int i = 0; i < array1.length; i++)
{
if (array1[i] != array2[i])
equal = false;
}
Because we already checked that the lengths were the same, we can use either value for both array lengths. It doesn't matter which one you use. By inserting this for loop into our if statement from before, we have a simple algorithm to test if two arrays are equal or not. You do another if statement at the bottom to print out your result based on the boolean variable equal. | ||
Code | ||
