This syntax seems strange

Question

I noticed some new syntax in this video:
```C#
while ((line = reader.ReadLine()) != null)
{
    string[] values = line.Split(',');
    soccerResults.Add(values);
}
```
It seems like we're simultaneously assigning a variable and also checking a boolean condition. Is this a C# only thing or is it possible to do this in other languages? Is there a word for this?

Jennifer Nordell · Accepted Answer

Hi there, @Brendan Whiting (https://teamtreehouse.com/brendanwhiting) ! To be honest, I'm not sure if this has a name or not, but this syntax is found in the MSDN ReadLine() documentation (https://docs.microsoft.com/en-us/dotnet/api/system.console.readline?redirectedfrom=MSDN&view=netframework-4.7.2#System_Console_ReadLine).
That being said, I know you have some points in PHP, and the same sort of thing can also be done there.
Let's say I have this (in PHP):
```php
if($student = "Jennifer")
```
Now normally, we want the double equals to make a comparison, but this is also valid syntax. And what it's saying is "if the assignment to the $student variable contains a truthy value, evaluate this as true".  This sort of thing helps prevent things like null, empty strings etc.
The same sort of thing is happening here. We're making an assignment inside the conditional and then asking if that assignment was null. Luckily, ReadLine() does almost exactly what we would expect by the name. It reads a line of text and returns a string. If it's out of lines, it returns a null. This code says, "while there are still lines left to be read, read the next line. When there are no more lines, stop."
Hope this helps! :sparkles:

benovarghese · Answer

would it assign a -1 to line when it reaches end of file or does -1 only apply if we were using peek()?

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Brendan Whiting

Brendan Whiting

This syntax seems strange

Ole Vølund Skov Mortensen

Ole Vølund Skov Mortensen

2 Answers

Jennifer Nordell

Jennifer Nordell

Brendan Whiting

Brendan Whiting

benovarghese

benovarghese