C++ Debugging

1. Using Assertions

• Assertions are a good mechanism to test the conditions in a program that are expected to be true.
• If an assert statement fails then program in aborted with a message.
• This can be used a good source for debugging during development.
• Asserts can be quietly turned off when production code is to be released.
• Use "bcc32 -DNDEBUG filename.cpp" to turn off aserts.
• Alternatively include "define NDEBUG" before #include for assert.h to turn off asserts.

EXAMPLE: Demonstrate the use of asserts for debugging

#include <iostream>

//#define NDEBUG
#include <assert.h>

using namespace std;

void main (int argc, char* argv[])
{
    assert ( argc == 3 );

    int a = atoi(argv[1]);
    int b = atoi(argv[2]);

    assert ( a == b );

    cout << a << endl;
    cout << b << endl;
}

INPUT:
filename.exe 1

OUTPUT:
Assertion failed: argc == 3, file assrt.cpp, line 10

Abnormal program termination

INPUT:
filename.exe 1 2

OUTPUT:
Assertion failed: a == b, file assrt.cpp, line 15

Abnormal program termination

INPUT:
filename.exe 1 1

OUTPUT:
1
1