Strcpy c ошибка

Answers

• ps = new char[strlen(animal) + 1];  // get new storage
  strcpy_s(ps, sizeof(animal), animal);         // copy string to new storag

  You allocate strlen(animal) of space for the ps variable, and then in the next line of code, lie to the strcpy_s function and state that you allocated sizeof(animal) number of characters.

  • Edited by
    Brian Muth
    Tuesday, August 11, 2015 7:09 PM
  • Marked as answer by
    Shu 2017
    Monday, August 24, 2015 6:00 AM

• Hi ClassicalGuitar,

  If you can guarantee that the destination string has enough space to hold the source string including its null-terminator, just use strcpy() and ignore the compiling warning; if the compiling warning is carking, suppress it with
  #define _CRT_SECURE_NO_WARNINGS
  or
  #pragma warning(disable : 4996)

  You may also use
  #define _CRT_SECURE_CPP_OVERLOAD_STANDARD_NAMES 1
  to let the compiler automatically replaces strcpy() with strcpy_s() for you. See at
  https://msdn.microsoft.com/en-us/library/ms175759.aspx

  From the MSDN document about strcpy() and strcpy_s(), the main difference between both is that, if the destination space is not enough, while strcpy() proceeds in silence, strcpy_s() calls default Invalid Parameter Handler Routine to consciously crash the
  program and make you be awared of it with a report; see at
  https://msdn.microsoft.com/en-us/library/ksazx244.aspx.

  You may overload the Invalid Parameter Handler Routine with your own function that not terminating the execution; in the case, strcpy_s() returns error; you are required to handle the program flow when the error happens.

  If the destination and source strings overlap, the behaviors of strcpy() and strcpy_s() are undefined.

  • Marked as answer by
    Shu 2017
    Monday, August 24, 2015 6:00 AM

• Reply both to Igor Tandetnik and kwick:

  Read documentation for warning C4996

  In C++, the easiest way to do that is to use Secure Template Overloads, which in many cases will eliminate deprecation warnings by replacing calls to deprecated functions
  with calls to the new secure versions of those functions. For example, consider this deprecated call to
  strcpy:

     char szBuf[10]; 
     strcpy(szBuf, "test"); // warning: deprecated 
  

  Defining _CRT_SECURE_CPP_OVERLOAD_STANDARD_NAMES as 1 eliminates the warning by changing the
  strcpy call to strcpy_s, which prevents buffer overruns. For more information, see
  Secure Template Overloads.

  The template overloads provide additional choices. Defining _CRT_SECURE_CPP_OVERLOAD_STANDARD_NAMES to 1 enables template overloads of standard CRT functions that call the more secure variants automatically. If
  _CRT_SECURE_CPP_OVERLOAD_STANDARD_NAMES is 1, then no changes to the code are necessary. Behind the scenes, the call to
  strcpy will be changed to a call to strcpy_s with the size argument supplied automatically.

  It is better for me to use a #define _CRT_SECURE_CPP_OVERLOAD_STANDARD_NAMES 1

  Now code becomes:

  // ptrstr.cpp -- using pointers to strings
  #define _CRT_SECURE_CPP_OVERLOAD_STANDARD_NAMES 1
  #include <iostream>
  #include <cstring>              // declare strlen(), strcpy()
  int main()
  {
      using namespace std;
      char animal[20] = "bear";   // animal holds bear
      const char * bird = "wren"; // bird holds address of string
      char * ps;                  // uninitialized
  
      cout << animal << " and ";  // display bear
      cout << bird << "n";       // display wren
      // cout << ps << "n";      //may display garbage, may cause a crash
  
      cout << "Enter a kind of animal: ";
      cin >> animal;              // ok if input < 20 chars
      // cin >> ps; Too horrible a blunder to try; ps doesn't
      //            point to allocated space
  
      ps = animal;                // set ps to point to string
      cout << ps << "!n";       // ok, same as using animal
      cout << "Before using strcpy():n";
      cout << animal << " at " << (int *) animal << endl;
      cout << ps << " at " << (int *) ps << endl;
  
      ps = new char[strlen(animal) + 1];  // get new storage
      strcpy(ps, animal);         // copy string to new storage
      cout << "After using strcpy():n";
      cout << animal << " at " << (int *) animal << endl;
      cout << ps << " at " << (int *) ps << endl;
      delete [] ps;
      cin.get();
      cin.get();
      return 0; 
  }
  

  and compiles and run without errors.
  

  This issue is solved!

  • Marked as answer by
    ClassicalGuitar
    Friday, August 28, 2015 5:27 PM

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