man/assert.3

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  34 .\"     @(#)assert.3    8.1 (Berkeley) 6/9/93
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  36 .Dd June 9, 1993
  37 .Dt ASSERT 3
  38 .Os
  39 .Sh NAME
  40 .Nm assert
  41 .Nd expression verification macro
  42 .Sh SYNOPSIS
  43 .Fd #include <assert.h>
  44 .Fn assert expression
  45 .Sh DESCRIPTION
  46 The
  47 .Fn assert
  48 macro tests the given
  49 .Ar expression
  50 and if it is false,
  51 the calling process is terminated.
  52 A
  53 diagnostic message is written to
  54 .Em stderr
  55 and the
  56 .Xr abort 3
  57 function is called, effectively terminating the program.
  58 .Pp
  59 If
  60 .Ar expression
  61 is true,
  62 the
  63 .Fn assert
  64 macro does nothing.
  65 .Pp
  66 The
  67 .Fn assert
  68 macro
  69 may be removed at compile time with
  70 the
  71 .Xr cc 1
  72 option
  73 .Fl DNDEBUG .
  74 .Sh DIAGNOSTICS
  75 The following diagnostic message is written to
  76 .Em stderr
  77 if
  78 .Ar expression
  79 is false:
  80 .Bd -literal -offset indent
  81 "assertion \e"%s\e" failed: file \e"%s\e", line %d\en", \e
  82                     "expression", __FILE__, __LINE__);
  83 .Ed
  84 .Sh SEE ALSO
  85 .Xr cc 1 ,
  86 .Xr abort 3
  87 .Sh STANDARDS
  88 The
  89 .Fn assert
  90 macro conforms to
  91 .St -ansiC .
  92 .Sh HISTORY
  93 A
  94 .Nm assert
  95 macro appeared in
  96 .At v6 .