I am working on a project where there is a lot of old code written for Windows.
On several places in the code i run in to the following situation.
The compiler throws an error at me saying i is not declared for the second for-loop. I am willing to agree with the compiler.
But since this code has been around for a long time I am suspecting that this actually worked at some time.
My question is if this was a thing in old-style C or C++? For me it looks really odd.
Sorry for getting off the topic of Handmade hero in this post I just thought this was a good forum to ask this type of question.
Also, love this project and I want to thank Casey for clarifying so much stuff.
On several places in the code i run in to the following situation.
1 2 3 4 5 6 7 8 9 10 11 | for(int i=0;i < 10; i++)
{
// does stuff
}
// a couple of lines
for(i=0; i < 20; i++)
{
// does stuff with variable i that was declared in the previous for-loop
}
|
The compiler throws an error at me saying i is not declared for the second for-loop. I am willing to agree with the compiler.
But since this code has been around for a long time I am suspecting that this actually worked at some time.
My question is if this was a thing in old-style C or C++? For me it looks really odd.
Sorry for getting off the topic of Handmade hero in this post I just thought this was a good forum to ask this type of question.
Also, love this project and I want to thank Casey for clarifying so much stuff.
Edited by Pete
on
Reason: Code formatting
That used to be valid code. That's why you can see Casey doing for loops like this in some early videos:
That way the `i` is guaranteed not to stick around after the for loop.
1 2 3 | {for(int i = 0; i < 10; ++i)
{
}}
|
That way the `i` is guaranteed not to stick around after the for loop.
It was valid code only with Visual Studio. In C that was never a valid code.
Not sure how far back it goes, but Visual Studio 6 allowed that. Starting with next version of Visual Studio (2005) they disabled this behavior by default.
You can still enable old behavior by using /Za, /Zc, /Zc:forScope compiler argumnets - https://msdn.microsoft.com/en-us/library/84wcsx8x.aspx Even in latest Visual Studio 2015.
Another "trick" some people used to avoid this behavior in old VS6 was to redefine for keyword:
This forces compiler to put for variable in scope of else statement and it doesn't go outside of it.
Not sure how far back it goes, but Visual Studio 6 allowed that. Starting with next version of Visual Studio (2005) they disabled this behavior by default.
You can still enable old behavior by using /Za, /Zc, /Zc:forScope compiler argumnets - https://msdn.microsoft.com/en-us/library/84wcsx8x.aspx Even in latest Visual Studio 2015.
Another "trick" some people used to avoid this behavior in old VS6 was to redefine for keyword:
1 | #define for if (0) {} else for
|
This forces compiler to put for variable in scope of else statement and it doesn't go outside of it.
Edited by Mārtiņš Možeiko
on