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I have read many answers on stackoverflow and codereview that says we should not use C style arrays with C++. What is reason for it ? If I use std::Array instead of C style array, will it impact on speed/performance ?

In my organization, entire application is written in C++. But only C style arrays are used.

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    Theoretically there's no penalty using std::array over a C-style array, and practically I doubt it as well (as long as you don't pass the array by value, which is possible with std::array but not with a C-style array). Commented Sep 23, 2019 at 11:36
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    Glad to see my gold "arrays" badge getting some use 🤪 Commented Sep 23, 2019 at 11:37
  • @Someprogrammerdude In C I can create variable length array at runtime like int arr[n]. Is it possible with std::array ? Commented Sep 23, 2019 at 11:41
  • @KamalPancholi VLAs are not allowed in standard C++. Commented Sep 23, 2019 at 11:44
  • @KamalPancholi For that you have std::vector. Commented Sep 23, 2019 at 11:47

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No, it will not have impact on performance. There are two reasons to use std::array instead C-like arrays:

  • Method at() that allows to get an element by index with bounds checking. Beware, operator [] doesn't have bounds checking.
  • Limited pointer arithmetic. It's much harder to shoot in the foot than with C-like arrays.
  • Same behavior as other std containers, like begin(), end(), size() methods without necessity to handle two variables: pointer and size. So, you can implement one algorithm that can work with arrays and other containers.

Thanks Thomas Sablik for clarification in comments.

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@ThomasSablik Yes, but the problem with simple C-style arrays is that they too often decay to pointers, and then std::begin() and std::end() won't work very well.

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