assert

This question already has an answer here: What does the Java assert keyword do, and when should it be used? 18 answers What does assert do? For example in the function: private static int charAt(String s, int d) { assert d >= 0 && d <= s.length(); if (d == s.length()) return -1; return s.charAt(d); } If you launch your program with -enableassertions (or -ea for short) then this statement assert cond; is equivalent to if (!cond) throw new AssertionError(); If you launch your program without this option, the assert statement will have no effect. For example, assert d >= 0 && d <= s.length(); ,

There's a discussion going on over at comp.lang.c++.moderated about whether or not assertions, which in C++ only exist in debug builds by default, should be kept in production code or not. Obviously, each project is unique, so my question here is not so much whether assertions should be kept, but in which cases this is recommendable/not a good idea. By assertion, I mean: A run-time check that tests a condition which, when false, reveals a bug in the software. A mechanism by which the program is halted (maybe after really minimal clean-up work). I'm not necessarily talking about C or C++. My

I have been reading some source code and in several places I have seen the usage of assert . What does it mean exactly? What is its usage? The assert statement exists in almost every programming language. It helps detect problems early in your program, where the cause is clear, rather than later as a side-effect of some other operation. When you do... assert condition ... you're telling the program to test that condition, and immediately trigger an error if the condition is false. In Python, it's roughly equivalent to this: if not condition: raise AssertionError() Try it in the Python shell: >