/Zc:forScope (Force Conformance in for Loop Scope)
Used to implement standard C++ behavior for for loops with Microsoft extensions (/Ze). /Zc:forScope is on by default.
/Zc:forScope[-]
Remarks
Standard behavior is to let a for loop's initializer go out of scope after the for loop. Under /Za, /Ze (Disable Language Extensions), the for loop's initializer remains in scope until the local scope ends.
The following code will compile under /Ze but not under /Za:
// zc_forScope.cpp
// compile with: /Zc:forScope- /Za
// C2065 expected
int main() {
// Uncomment the following line to resolve.
// int i;
for (int i =0; i < 1; i++)
;
i = 20; // i has already gone out of scope under /Za
}
If you use /Zc:forScope-, you will get a warning (off by default) if a variable is in scope because of a declaration that was made in a previous scope. To demonstrate this, remove the // characters in the above code to declare int i.
You can modify the run-time behavior of /Zc:forScope with the conform pragma.
If you use /Zc:forScope- in a project with an existing .pch file, /Zc:forScope- is ignored (with a warning) and compilation continues with the existing .pch files. If you want a new .pch file generated, use /Yc (Create Precompiled Header File).
For more information about conformance issues with Visual C++, see Nonstandard Behavior.
To set this compiler option in the Visual Studio development environment
Open the project's Property Pages dialog box. For details, see Working with Project Properties.
Click the C/C++ folder.
Click the Language property page.
Modify the Force Conformance in For Loop Scope property.