discouraged.md

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Disallowed functions

1. Strongly prefer C++ standard library facilities over C library functions, unless the latter absolutely cannot be avoided. In particular, aim to avoid all memory and string handling by C functions.

   Example:

   • std::memcpy() should be usually replaced by a call to std::copy(). The latter optimizes down to a std::memcpy() call in cases where POD types are to be copied, and is applicable in more situations (e.g. involving non-trivial copy constructors).

   • String handling should be done by using std::string. Avoid using const char* solutions and the use of any of the unsafe str* functions, unless there is a proven need to due performance considerations. This should be a very rare case.

2. Do not use the old C facilities (rand(), RAND_MAX) for random number generation, since they give no guarantees on the quality of the randomness of the generated values, which can be arbitrarily bad. Use std::mt19937 (Mersenne Twister) from <random> by default, and other generators if you can justify their use over std::mt19937.

3. Do not use any of the following standard library functions, since they are officially removed from C++ 17 with the adoption of N4190: auto_ptr<>, random_shuffle(), ptr_fun(), mem_fun(), mem_fun_ref(), bind1st(), bind2nd(), unary_function, binary_function.

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