Smart pointers and initialization

Asked Feb 13 '23 at 19:47

Active Feb 13 '23 at 20:02

Viewed 109 times

int number_of_elements = 5;
std::shared_ptr<int[]> dataholder;
dataholder = std::make_shared<int[]>(number_of_elements);

for (int i = 0; i < number_of_elements; i++) 
    dataholder[i] = rand() % 100; // -----> This line

for (int i = 0; i < number_of_elements; i++) 
    std::cout<< dataholder.get()[i] <<'\n';

printf("Success");

I want the smart point of type int[] to contain 5 random integers, but I have an issue with this line

dataholder[i] = rand() % 100;

it causes

malloc(): corrupted top size
Process finished with exit code 134 (interrupted by signal 6: SIGABRT)

How can I do to fix this issue?

edited Feb 13 '23 at 20:02

sweenish

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asked Feb 13 '23 at 19:47

koolaid

2

any reason you are not using a `std::vector` ? – 463035818_is_not_an_ai Feb 13 '23 at 19:49
All attempts to create smart pointers to arrays of unspecified size are guaranteed to end in tears. This does not do what everyone who tries that thinks it will do. – Sam Varshavchik Feb 13 '23 at 19:50
2

https://stackoverflow.com/questions/13061979/shared-ptr-to-an-array-should-it-be-used – 463035818_is_not_an_ai Feb 13 '23 at 19:54
Possible dup? https://stackoverflow.com/questions/13794447/can-you-allocate-an-array-with-something-equivalent-to-make-shared – Slava Feb 13 '23 at 19:56
1

@Slava according to that answer OPs code should be fine since C++20 – 463035818_is_not_an_ai Feb 13 '23 at 19:58
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what compiler are you using? Which c++ standard are you using? – 463035818_is_not_an_ai Feb 13 '23 at 19:58
works fine here https://godbolt.org/z/8Gcq1Yavf – 463035818_is_not_an_ai Feb 13 '23 at 20:00
2

@463035818_is_not_a_number I agree, we need [mcve] and compiler/settings info – Slava Feb 13 '23 at 20:01
This works in both clang++ 15 and g++ 12.2 when compiled using the C++20 standard. I don't quite see the why of this question (vectors exist), but it works. I would also suggest choosing one method to print to the terminal. – sweenish Feb 13 '23 at 20:08
it works because since C++20. Before it just does not compile, hence I have no clue how to reproduce the issue – 463035818_is_not_an_ai Feb 13 '23 at 20:10
Although your code seems to work fine in VS2022 as is, maybe Change `dataholder = std::make_shared(number_of_elements);` to `dataholder = std::make_shared();` (if you can make number_of_elements const) – user20716902 Feb 13 '23 at 20:12
g++ 9.4.0 compiler – koolaid Feb 13 '23 at 20:32
What is the command line you are using to compile the code? And does your compiler support what you are trying to do (because your compiler is several version back)? – Eljay Feb 13 '23 at 22:05
I have gcc 11.3 and even that fails to compile "static assertion failed: make_shared not supported", I do not see how 9.4.0 would compile that – Slava Feb 14 '23 at 00:05

Smart pointers and initialization

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