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can't create checksum algorithm/ can't understand concept of checksum
Here is my code:
int[] a = {1, 2, 3, 4, 5} checksum = 0; int i = 0; while ( a[i] < a.length-1 ) { checksum += a[i] + a[i - 1] ; i++; } checksum %= i;
Another problem is I can't really grasp what a "checksum" is. I've looked it up but don't get it. Could I have a simple example please? I need to fix my code ASAP.
Related threads:
Re: can't create checksum algorithm/ can't understand concept of checksum
There are many different ways to implement a checksum. See: Wikipedia: List of Checksums.
Re: can't create checksum algorithm/ can't understand concept of checksum
An implementation of a checksum varies, however its goal is always the same: To determine if data has been transported without errors or not.
To show the the basic idea of a checksum, i've written a simple example which uses a very basic "summation" checksum, which computes the checksum based on the sum of all the payload bytes. Via the comments, assume this data array is transferred across a socket or whatever.
public static void main(String[] args){ //SENDER final byte[] data = new byte[4]; data[0] = 1; data[1] = 2; data[2] = 3; //calculate checksum for(int i = 0; i < data.length-1; i++){ data[data.length-1] += data[i]; } //RECEIVER final byte[] received = data; //calculate checksum byte checksum = 0; for(int i = 0; i < data.length-1; i++){ checksum += received[i]; } //CHECKSUM DOESNT MATCH! DATA CORRUPTED! if(checksum != received[4]){ System.out.println("An error occured"); } }
Please use [highlight=Java]//code goes here...[/highlight] tags when posting your code
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