Go back to Richel Bilderbeek's homepage.
Go back to Richel Bilderbeek's C++ page.
assert is a macro to do run-time debugging checks.
After debugging, #define NDEBUG
to let the preprocessor remove all asserts from your code.
Make use of assert [1-5].
The use of assert statements can help to
document the assumptions you make when implementing your code [6].
assert is #defined in cassert.h.
Example
A division will only succeed if the denominator is unequal to zero. In your code, you will have to take care that a division by zero never occurs. Using assert, as shown in the code below, will take you to the problem directly.
Example user-defined assert
//---------------------------------------------------------------------------
/*
Assert, a custom assert macro
Copyright (C) 2011 Richel Bilderbeek
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
//---------------------------------------------------------------------------
//From http://www.richelbilderbeek.nl/CppAssert.htm
//---------------------------------------------------------------------------
#ifndef BILDERBIKKEL_ASSERT_H
#define BILDERBIKKEL_ASSERT_H
//---------------------------------------------------------------------------
//From http://www.richelbilderbeek.nl/CppAssert.htm
#ifdef NDEBUG_BILDERBIKKEL
#define Assert(x) ((void)0)
#else
#include <fstream>
#include <iostream>
#include <stdexcept>
#define Assert(x) \
if (!(x)) \
{ \
std::cout \
<< "ERROR!! Assertion " \
<< std::string (#x) \
<< " failed
on line " \
<< (__LINE__) \
<< "
in file " \
<< __FILE__ \
<< std::endl; \
std::ofstream f("assert_out.txt"); \
f \
<< "ERROR!! Assertion " \
<< std::string (#x) \
<< " failed
on line " \
<< (__LINE__) \
<< "
in file " \
<< __FILE__ \
<< std::endl; \
f.close(); \
throw std::logic_error( \
"Assertion failed"); \
}
#endif
//---------------------------------------------------------------------------
#endif // BILDERBIKKEL_ASSERT_H
|
User-defined asserts for specific IDE's
- Assert in a C++ Builder console Application
- Assert in a Qt Creator console Application
- Herb Sutter, Andrei Alexandrescu. C++ coding standards: 101 rules, guidelines, and best practices. ISBN: 0-32-111358-6. Chapter 68: 'Assert liberally to document internal assumptions and invariants'
- Bjarne Stroustrup. The C++ Programming Language (3rd edition). 1997. ISBN: 0-201-88954-4. Advice 24.5.18: 'Explicitly express preconditions, postconditions, and other assertions as assertions'
- Steve McConnell. Code Complete (2nd edition). 2004. ISBN: -735619670. Chapter 8.2 'Assertions', paragraph 'Guidelines for using asserts': 'Use assertions to document and verify preconditions and postconditions'
- Steve McConnell. Code Complete (2nd edition). 2004. ISBN: -735619670. Chapter 8.2 'Assertions', paragraph 'Guidelines for using asserts': 'Use assertions for conditions that should never occur'.
- Jesse Liberty. Sams teach yourself C++ in 24 hours. ISBN: 0-672-32224-2. Hour 24, chapter 'assert()': 'Use assert freely'
- John Lakos. Large-Scale C++ Software Design. 1996. ISBN: 0-201-63362-0. Chapter 2.6: 'The use of assert statements can help to document the assumptions you make when implementing your code<'/li>
assert.h
//---------------------------------------------------------------------------
/*
Assert, a custom assert macro
Copyright (C) 2011 Richel Bilderbeek
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
//---------------------------------------------------------------------------
//From http://www.richelbilderbeek.nl/CppAssert.htm
//---------------------------------------------------------------------------
#ifndef BILDERBIKKEL_QT_ASSERT_H
#define BILDERBIKKEL_QT_ASSERT_H
//---------------------------------------------------------------------------
//From http://www.richelbilderbeek.nl/CppAssert.htm
#ifdef NDEBUG_BILDERBIKKEL
#define Assert(x) ((void)0)
#else
#include <fstream>
#include <iostream>
#include <stdexcept>
#define Assert(x) \
if (!(x)) \
{ \
std::cout \
<< "ERROR!! Assertion " \
<< std::string (#x) \
<< " failed\n on line " \
<< (__LINE__) \
<< "\n in file " \
<< __FILE__ \
<< std::endl; \
std::ofstream f("assert_out.txt"); \
f \
<< "ERROR!! Assertion " \
<< std::string (#x) \
<< " failed\n on line " \
<< (__LINE__) \
<< "\n in file " \
<< __FILE__ \
<< std::endl; \
f.close(); \
throw std::logic_error( \
"Assertion failed"); \
}
#endif
//---------------------------------------------------------------------------
#endif // BILDERBIKKEL_QT_ASSERT_H
|
Go back to Richel Bilderbeek's C++ page.
Go back to Richel Bilderbeek's homepage.
This page has been created by the tool CodeToHtml