22b4470f2a
Update all links to C++ Core Guidelines to `e49158a`.
Refresh done using the following script and some manual edits:
db76e34e74/personal/fred-tingaud/rspec/refresh-cppcoreguidelines.py
When re-using this script, be mindful that:
- it does not cover `shared_content`
- it does not properly escape inline code in links (e.g., "[=]" or "`mutex`es")
- it does not change `C++` to `{cpp}` in link titles.
Co-authored-by: Marco Borgeaud <marco.borgeaud@sonarsource.com>
63 lines
2.5 KiB
Plaintext
63 lines
2.5 KiB
Plaintext
== Why is this an issue?
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C-style arrays (such as ``++int i[10]++``) are not very convenient to use:
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* They are fixed size (even C Variable Length Arrays are not truly variable size, and they are not supported in {cpp})
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* If the number of elements in the array can vary, it will lead to manual memory allocation (or people will use fixed-size arrays that "should be large enough", which is both a waste of memory and a limitation of the program)
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* It is very easy to lose the size of the array since an array passed to a function decays into a pointer
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The {cpp} standard library proposes two types that are better than C-style arrays and together cover all the use cases of C-style arrays:
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* For fixed-size arrays, where the memory is on the stack, use ``++std::array++``. It is like a C-style array, except that it has normal argument passing semantics, and the size is always a part of the type. You can roll your version if ``++std::array++`` is unavailable to you (before {cpp}11).
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* For variable-size arrays, use ``++std::vector++``. It can be resized and handles memory allocation transparently.
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* For character strings, you should use ``++std::string++`` instead of arrays of characters.
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* For arrays of characters that are not strings (e.g., alphabet, exit codes, keyboard control list), prefer ``++std::array++`` or ``++std::vector++`` as per the first two bullets.
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The rule S945 is related to this rule but focuses on passing arguments of an array type. S5025 will flag the use of dynamic memory allocation that could be replaced by ``++std::vector++``.
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=== Noncompliant code example
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[source,cpp]
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----
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void f() {
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int a[10]; // Noncompliant
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}
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----
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=== Compliant solution
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[source,cpp]
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----
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void f() {
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std::array<int, 10> a1; // If the size really is a constant
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// Or
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std::vector<int>a2; // For variable size
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auto s = "Hello!"; // Compliant by exception
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}
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----
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=== Exceptions
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This rule will not report the use of C-style arrays in ``++extern "C"++`` code (since those arrays are often required here for compatibility with external code) and in the arguments of ``++main++``.
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== Resources
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* {cpp} Core Guidelines - https://github.com/isocpp/CppCoreGuidelines/blob/e49158a/CppCoreGuidelines.md#slcon1-prefer-using-stl-array-or-vector-instead-of-a-c-array[SL.con.1: Prefer using STL `array` or `vector` instead of a C array]
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ifdef::env-github,rspecator-view[]
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'''
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== Comments And Links
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(visible only on this page)
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=== relates to: S945
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=== relates to: S5025
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endif::env-github,rspecator-view[]
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