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28 .\" @(#)assert.3 8.1 (Berkeley) 6/9/93
36 .Nd expression verification macro
46 the calling process is terminated.
47 A diagnostic message is written to
51 is called, effectively terminating the program.
63 may be removed at compile time by defining
69 .Fl D Ns Dv NDEBUG ) .
70 Unlike most other include files,
72 may be included multiple times.
73 Each time whether or not
75 is defined determines the behavior of assert from that point forward
76 until the end of the unit or another include of
81 macro should only be used for ensuring the developer's expectations
83 It is not appropriate for regular run-time error detection.
87 generates a diagnostic message similar to the following:
88 .Dl "Assertion failed: (1 == 0), function main, file main.c, line 100."
90 The following assert tries to assert there was no partial read:
91 .Dl "assert(read(fd, buf, nbytes) == nbytes);"
92 However, there are two problems.
93 First, it checks for normal conditions, rather than conditions that
95 Second, the code will disappear if
97 is defined, changing the semantics of the program.