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Name

assert - verify program assertion

Synopsis

#include <assert.h>

void assert(int expression);

MT-Level

Safe

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. The latter are respectively the values of the preprocessor macros __FILE__ and __LINE__ .

Compiling with the preprocessor option -DNDEBUG (see cc(1B) ), or with the preprocessor control statement #define NDEBUG ahead of the #include <assert.h> statement, will stop assertions from being compiled into the program.

See Also

cc(1B) , abort(3C) , gettext(3I) , setlocale(3C)

Notes

If the application is linked with -lintl, then messages printed from this function are in the native language specified by the LC_MESSAGES locale category; see setlocale(3C) .

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

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