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1.. title:: clang-tidy - modernize-avoid-c-arrays2 3modernize-avoid-c-arrays4========================5 6`cppcoreguidelines-avoid-c-arrays` redirects here as an alias for this check.7 8`hicpp-avoid-c-arrays` redirects here as an alias for this check.9 10Finds C-style array types and recommend to use ``std::array<>`` /11``std::vector<>``. All types of C arrays are diagnosed.12 13For parameters of incomplete C-style array type, it would be better to14use ``std::span`` / ``gsl::span`` as replacement.15 16However, fix-it are potentially dangerous in header files and are therefore not17emitted right now.18 19.. code:: c++20 21 int a[] = {1, 2}; // warning: do not declare C-style arrays, use 'std::array' instead22 23 int b[1]; // warning: do not declare C-style arrays, use 'std::array' instead24 25 void foo() {26 int c[b[0]]; // warning: do not declare C VLA arrays, use 'std::vector' instead27 }28 29 template <typename T, int Size>30 class array {31 T d[Size]; // warning: do not declare C-style arrays, use 'std::array' instead32 33 int e[1]; // warning: do not declare C-style arrays, use 'std::array' instead34 };35 36 array<int[4], 2> d; // warning: do not declare C-style arrays, use 'std::array' instead37 38 using k = int[4]; // warning: do not declare C-style arrays, use 'std::array' instead39 40 41However, the ``extern "C"`` code is ignored, since it is common to share42such headers between C code, and C++ code.43 44.. code:: c++45 46 // Some header47 extern "C" {48 49 int f[] = {1, 2}; // not diagnosed50 51 int j[1]; // not diagnosed52 53 inline void bar() {54 {55 int j[j[0]]; // not diagnosed56 }57 }58 59 }60 61Similarly, the ``main()`` function is ignored. Its second and third parameters62can be either ``char* argv[]`` or ``char** argv``, but cannot be63``std::array<>``.64 65Options66-------67 68.. option:: AllowStringArrays69 70 When set to `true` (default is `false`), variables of character array type71 with deduced length, initialized directly from string literals, will be ignored.72 This option doesn't affect cases where length can't be deduced, resembling73 pointers, as seen in class members and parameters. Example:74 75 .. code:: c++76 77 const char name[] = "Some name";78