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.. title:: clang-tidy - misc-suspicious-string-compare
misc-suspicious-string-compare
==============================
Find suspicious usage of runtime string comparison functions.
This check is valid in C and C++.
Checks for calls with implicit comparator and proposed to explicitly add it.
.. code-block:: c++
if (strcmp(...)) // Implicitly compare to zero
if (!strcmp(...)) // Won't warn
if (strcmp(...) != 0) // Won't warn
Checks that compare function results (i,e, ``strcmp``) are compared to valid
constant. The resulting value is
.. code::
< 0 when lower than,
> 0 when greater than,
== 0 when equals.
A common mistake is to compare the result to `1` or `-1`.
.. code-block:: c++
if (strcmp(...) == -1) // Incorrect usage of the returned value.
Additionally, the check warns if the results value is implicitly cast to a
*suspicious* non-integer type. It's happening when the returned value is used in
a wrong context.
.. code-block:: c++
if (strcmp(...) < 0.) // Incorrect usage of the returned value.
Options
-------
.. option:: WarnOnImplicitComparison
When non-zero, the check will warn on implicit comparison. `1` by default.
.. option:: WarnOnLogicalNotComparison
When non-zero, the check will warn on logical not comparison. `0` by default.
.. option:: StringCompareLikeFunctions
A string specifying the comma-separated names of the extra string comparison
functions. Default is an empty string.
The check will detect the following string comparison functions:
`__builtin_memcmp`, `__builtin_strcasecmp`, `__builtin_strcmp`,
`__builtin_strncasecmp`, `__builtin_strncmp`, `_mbscmp`, `_mbscmp_l`,
`_mbsicmp`, `_mbsicmp_l`, `_mbsnbcmp`, `_mbsnbcmp_l`, `_mbsnbicmp`,
`_mbsnbicmp_l`, `_mbsncmp`, `_mbsncmp_l`, `_mbsnicmp`, `_mbsnicmp_l`,
`_memicmp`, `_memicmp_l`, `_stricmp`, `_stricmp_l`, `_strnicmp`,
`_strnicmp_l`, `_wcsicmp`, `_wcsicmp_l`, `_wcsnicmp`, `_wcsnicmp_l`,
`lstrcmp`, `lstrcmpi`, `memcmp`, `memicmp`, `strcasecmp`, `strcmp`,
`strcmpi`, `stricmp`, `strncasecmp`, `strncmp`, `strnicmp`, `wcscasecmp`,
`wcscmp`, `wcsicmp`, `wcsncmp`, `wcsnicmp`, `wmemcmp`.
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