= != ==

So, they did add code to have us killed. Damn it!

@asgs you know, just in case

tag =/= category

Is it about = or == ?

@R1100 yes.

@sp1dey but the compiler would probably count this as an error

@R1100 in case of C/C++, nope

@Lensflare not just c/c++. This is often valid as a successfull non-null assignment. Java does this to if you do something like
if((line = readLine()) != Null){...}

And this is somewhat common still!

Java doesn't however implicitly cast to boolean nor allow int to be a truthy value (Python might work with this, I haven't tried that tho). So the above example would fail without the == null part

However if readLine() in this example returned boolean it would work. Which is also true with the case in the image because its a boolean assignment!

if(killAllHumans = true) {...} Is still evaluated as all around true and enters the IF statement just as in the pic!

I haven't tried this with C# but I suspect it prolly works there too.

@Hazarth I'm not sure about c# too. Modern languages tend to avoid this pitfall though. All you need to get rid of is assignment expressions evaluating to the assigned value. Normally nobody needs that anyway.

@Lensflare I had to check to be sure, this is from the official C# documentation, last updated 06/21/2029:

"...The result of an assignment expression is the value assigned to the left-hand operand..."

I don't have a C# environment setup so if you or someone could confirm It's true then I could be sure. But this is at least what the docs say.

@Hazarth Not sure about 2029, but currently it is like in Java: "if ( ( a = _b() ) == c )" definitely works and there is no implicit cast to bool, thus leading to a compiler error if the result of whole expression is of another type. For conditionals this can lead to the stated problems, but it's great for using-blocks: "using (new IDisposable a = _b() )"

@saucyatom great example with using. But 'using' has an alternative, cleaner syntax now.