What is the function of this statement *(long*)0=0;?

Question

In the following code, *(long*)0=0; is used along with the if clause, but what is its purpose?

if(r.wid*r.ht < tot)
    *(long*)         


        

Answer 1

To cause a program to 'exit abnormally', use the abort() function (http://pubs.opengroup.org/onlinepubs/9699919799/functions/abort.html).

The standard C/C++ idiom for "if condition X is not true, make the program exit abnormally" is the assert() macro. The code above would be better written:

assert( !(r.wid*r.ht < tot) );

or (if you're happy to ignore edge cases), it reads more cleanly as:

assert( r.wid*r.ht >= tot );