CODEWITHSUNDEEP
c++c++17
zhaozheng
zhaozheng

Reputation: 81

how to avoid to use memcpy to create a string

My programmer has lots of memcpy. I want to avoid them.

I want to get a struct like boost::string_ref. I want to know.

uint32_t len = 20;
char *p = new char[len];
memset(p, 0x00, len)
memcpy(p, "aaaa", 4);
string str(p, 4);// whether is use memcpy or not ?
const string str2(p, 4); //whether is use memcpy or not
//if it used memcpy, how to avoid memcpy ?

string_ref->string

string_view->string

string->string_ref

string->string_view

char* ->string

string->string

please tell me how to judge whether function used memcpy ?

Upvotes: 1

Views: 345

Answers (1)

Nikos C.
Nikos C.

Reputation: 51850

Use an std::string_view to avoid copying the string.

#include <string_view>
// ...

const string_view strview(p, 4);

Keep in mind that string views are not guaranteed to be null-terminated, so be careful when using them in APIs that expect a null-terminated char*. Also, when the string they are viewing goes out of scope, the string view itself becomes invalid (just like a pointer would.)

Upvotes: 2

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