/Zc:strictStrings
(Disable string literal type conversion)
When specified, the compiler requires strict const
-qualification conformance for pointers initialized by using string literals.
/Zc:strictStrings
[-
]
If /Zc:strictStrings
is specified, the compiler enforces the standard C++ const
qualifications for string literals, as type 'array of const char
' or 'array of const wchar_t
', depending on the declaration. String literals are immutable, and an attempt to modify the contents of one results in an access violation error at run time. You must declare a string pointer as const
to initialize it by using a string literal, or use an explicit const_cast
to initialize a non-const
pointer. By default, or if /Zc:strictStrings-
is specified, the compiler does not enforce the standard C++ const
qualifications for string pointers initialized by using string literals.
The /Zc:strictStrings
option is off by default. The /permissive-
compiler option implicitly sets this option, but it can be overridden by using /Zc:strictStrings-
.
Use the /Zc:strictStrings
option to prevent compilation of incorrect code. This example shows how a simple declaration error leads to a crash at run time:
// strictStrings_off.cpp
// compile by using: cl /W4 strictStrings_off.cpp
int main() {
wchar_t* str = L"hello";
str[2] = L'a'; // run-time error: access violation
}
When /Zc:strictStrings
is enabled, the same code reports an error in the declaration of str
.
// strictStrings_on.cpp
// compile by using: cl /Zc:strictStrings /W4 strictStrings_on.cpp
int main() {
wchar_t* str = L"hello"; // error: Conversion from string literal
// loses const qualifier
str[2] = L'a';
}
If you use auto
to declare a string pointer, the compiler creates the correct const
pointer type declaration for you. An attempt to modify the contents of a const
pointer is reported by the compiler as an error.
Lưu ý
The C++ Standard Library in Visual Studio 2013 does not support the /Zc:strictStrings
compiler option in debug builds. If you see several C2665 errors in your build output, this may be the cause.
For more information about conformance issues in Visual C++, see Nonstandard Behavior.
Open the project's Property Pages dialog box. For details, see Set C++ compiler and build properties in Visual Studio.
Select the Configuration Properties > C/C++ > Command Line property page.
Modify the Additional Options property to include
/Zc:strictStrings
and then choose OK.