.TH ASSERT 3 .SH NAME assert \- check program invariants .SH SYNOPSIS .B #include .br .B #include .PP .B #define assert if(cond);else _assert("cond") .PP .B void _assert(int cond) .SH DESCRIPTION .I Assert is a preprocessor macro that (via .IR _assert ) prints a message and calls .I abort when .I cond is false. .SH SOURCE .B /usr/local/plan9/src/libc/port/_assert.c