Share via

Compiler Warning (level 3) C4996

'function': was declared deprecated

The compiler encountered a function that was marked with deprecated. The function may no longer be supported in a future release. You can turn this warning off with the warning pragma (example below).

C4996 is generated for the line on which the function is declared and for the line on which the function is used.

You will see C4996 if you are using members of the <hash_map> and <hash_set> header files in the std namespace. See The stdext Namespace for more information.

Some CRT and Standard C++ Library functions have been deprecated in favor of new, more secure functions. For more information about deprecated functions, see Security Features in the CRT and Safe Libraries: Standard C++ Library.

C4996 can also occur if you use MFC or ATL functions that were deprecated for security reasons. To suppress these warnings, see _AFX_SECURE_NO_WARNINGS and _ATL_SECURE_NO_WARNINGS.

C4996 can also occur when you use the marshaling library. In this case C4996 is an error, not a warning. This error will occur when you use marshal_as to convert between two data types that require a marshal_context Class. You will also receive this error when the marshaling library does not support a conversion. For more information about the marshaling library, see Overview of Marshaling in C++.


The following sample generates C4996.

// C4996.cpp
// compile with: /W3
// C4996 warning expected
#include <stdio.h>

// #pragma warning(disable : 4996)
void func1(void) {
   printf_s("\nIn func1");

__declspec(deprecated) void func1(int) {
   printf_s("\nIn func2");

int main() {

C4996 can also occur if you do not use a checked iterator when compiling with _SECURE_SCL 1. See Checked Iterators for more information.

The following sample generates C4996.

// C4996_b.cpp
// compile with: /EHsc /W3 /c
#define _SECURE_SCL 1
#include <algorithm>
using namespace std;
using namespace stdext;
int main() {
   int a [] = {1, 2, 3};
   int b [] = {10, 11, 12};
   copy(a, a + 3, b + 1);   // C4996
// try the following line instead
//   copy(a, a + 3, b);
   copy(a, a + 3, checked_array_iterator<int *>(b, 3));   // OK

The following sample generates C4996 because the marshaling library requires a context to convert from a System::String to a const char *.

// C4996_Marshal.cpp
// compile with: /clr 
// C4996 expected
#include <stdlib.h>
#include <string.h>
#include <msclr\marshal.h>

using namespace System;
using namespace msclr::interop;

int main() {
   String^ message = gcnew String("Test String to Marshal");
   const char* result;
   result = marshal_as<const char*>( message );
   return 0;