NAME

assert − verify program assertion

SYNOPSIS

#include <assert.h>

assert (expression)
int expression;

DESCRIPTION

This macro is useful for putting diagnostics into programs.  When it is executed, if expression is false (zero), assert prints

“Assertion failed: expression, file xyz, line nnn”

on the standard error output and aborts.  In the error message, xyz is the name of the source file and nnn the source line number of the assert statement. 

Compiling with the preprocessor option −DNDEBUG [see cpp(1)], or with the preprocessor control statement “#define NDEBUG” ahead of the “#include <assert.h>” statement, stops assertions from being compiled into the program. 

SEE ALSO

cpp(1), abort(3C)

CAVEAT

Since assert is implemented as a macro, the expression may not contain any string literals. 

March 13, 1992