Start by stopping panicking - it never helps. Calm down, relax, and engage your brain! :laugh:
The first thing to do is learn to use the debugger: I can't give you explicit instructions because I don't know what system you are using and they all work differently, but they all have the same basic features. Google for the name of your development system (Visual Studio, Turbo C, whatever) and "debugger" and you should find instructions pretty easily.
Start with three things the debugger can do for you:
1) Breakpoint: when the application is running in the debugger and it reaches a line with a breakpoint, it stops, and passes control to you. Put a breakpoint in your code on this line:
l=strlen(arr);
and you'll be fine.
2) Variables: once the debugger has passed control to you, you can use it to view the variables and their content - even while you run the code!
3) Stepping: you can tell the debugger "execute the next one line of code" and it will.
Think of the development process as writing an email: compiling successfully means that you wrote the email in the right language - English, rather than German for example - not that the email contained the message you wanted to send.
So now you enter the second stage of development (in reality it's the fourth or fifth, but you'll come to the earlier stages later): Testing and Debugging.
Start by looking at what it does do, and how that differs from what you wanted. This is important, because it give you information as to why it's doing it. For example, if a program is intended to let the user enter a number and it doubles it and prints the answer, then if the input / output was like this:
Input Expected output Actual output
1 2 1
2 4 4
3 6 9
4 8 16
Then it's fairly obvious that the problem is with the bit which doubles it - it's not adding itself to itself, or multiplying it by 2, it's multiplying it by itself and returning the square of the input.
So with that, you can look at the code and it's obvious that it's somewhere here:
private int Double(int value)
{
return value * value;
}
Once you have an idea what might be going wrong, start using the debugger to find out why.
Think about what each line in the code should do before you execute it, and compare that to what it actually did when you use the "Step over" button to execute each line in turn. Did it do what you expect? If so, move on to the next line.
If not, why not? How does it differ?
This is a skill, and it's one which is well worth developing as it helps you in the real world as well as in development. And like all skills, it only improves by use!
Yes, I could probably tell you what "the problem" is - but it's not difficult to do this yourself, and you will learn something really worthwhile at the same time!