how to convert char ** to unique_ptr array?

Question

The old code is as below:

 char** wargv = new char*[argc];//memory leak! for(int k = 0; k < argc; ++k) { wargv[k] = new char[strlen(argv[k]) + 1]; strncpy(wargv[k], argv[k], strlen(argv[k])); wargv[k][strlen(argv[k])] = '\0'; }

because there may cause memory leak, so I want to convert wargv to unique_ptr. How to make it? I know how to convert char* to unique_ptr, the code below works:

int size_t = 10; std::unique_ptr<char[]> wargv(new char[size_t]{0}); strncpy(wargv.get(), "abcdef", size_t);

but I don't know how to convert char ** to unique_ptr, I tried vector,but it doesn't work.

Wouldn't it be better to use std::vector<std::string> instead? — Some programmer dude
– Some programmer dude, Commented Sep 23, 2021 at 7:20
See here - stackoverflow.com/questions/31135178/… - using array_ptr_type = std::unique_ptr<char[]>; using array_of_arrays_type = std::unique_ptr<array_ptr_type[]>; — moi
– moi, Commented Sep 23, 2021 at 7:20
I don't want to release the memory manually，the wargv will pass in another function. — hupantingxue
– hupantingxue, Commented Sep 23, 2021 at 7:23
You should not use size_t as a variable name. It is a standard type name. Besides, I recommend considering the suggestion of @Someprogrammerdude. — nielsen
– nielsen, Commented Sep 23, 2021 at 8:30
Using smart pointers for both "dimensions" will not solve the problem if you want to pass the result to a function expecting a char* arguments. Use standard C++ containers and strings as long as you can, then explicitly convert to the expected only when really needed. Use the (temporary) char** variable. Then explicitly free everything. — Some programmer dude
– Some programmer dude, Commented Sep 23, 2021 at 8:50

rustyhu · Accepted Answer · 2021-09-23 14:48:53Z

As @Some programmer dude commented, std::vector<std::string> should be a better choice than std::unique_ptr<>, with memory allocation management.

I try to write a simple example and it works well.

#include <iostream> #include <string> #include <vector> int main(int argc, char** argv) { std::vector<std::string> collection(argc); for (auto i = 0; i < argc; i++) { collection[i] = argv[i]; } for (const auto& arg : collection) { std::cout << arg << "\n"; } }

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