CODEWITHSUNDEEP
c#
user5405648
user5405648

Reputation:

Do I need to explicitly run an if statement before a while-loop?

I am fairly new to the C# language and wondered something when writing code not so long ago. When I am writing while loops, I also find asking myself do I explicitly need to check if my while condition is even needed, lets take the following code for example.

while (_myList.Count > 0)
{
    // do some work
}

If previously written code (by other developers) I have seen them do something like this...

if (_list.Count > 0)
{
    while (_myList.Count > 0)
    {
        // do some work
    }
}


Which is the best practice, do I even need to do this? If so why.. can someone shine some light on this topic and let me know whats best? Thanks.

Upvotes: 0

Views: 53

Answers (3)

Timon Post
Timon Post

Reputation: 2889

You don't have to specify the if:

if (_list.Count > 0)

While loop

What a while loop does: is taking an argument and compares whats left from the operator to the the right. And returns a boolean (true or false) as long the while gets a true it will continue the loop.

IF

What an if statment does: is taking an argument and compares whats left from the operator to the the right. And returns a boolean (true or false) as long the if gets a true it will continue and run the code in the if code block.

notice:

if (_list.Count > 0) // checking for _list
{
   while (_myList.Count > 0) // checking for _myList
   { 
   }
}

In the example you have shown the "Other developer" you check on different situations so in this case it can be usefull to check on _list.Count if you don't want to run te loop when _list.Count > 0.

Conclusion

Don't do: it when you checkking on teh same list in the if and wile.

Can do: if you only want to run the wile on an certain condition or possible exception.

Upvotes: 0

waka
waka

Reputation: 3417

The second code example is useless. If list count is 0 or smaller, the while wouldn't be executed.

However, you have to check, if _myList is null, maybe like this:

if (_myList == null)
    //error handling here

if _myList really was null, then you'd have a NullReferenceException in both your code examples.

Upvotes: 0

Arnaud F.
Arnaud F.

Reputation: 8452

No you don't need to add an if in this case.

Before entering while condition will be evaluated and you don't iterate if <= 0.

Caution in your sample you speak of _list and my_list which isn't the same object.

Upvotes: 0

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