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std::basic_string_view::data

From cppreference.com
 
 
 
 
constexpr const_pointer data() const;
(since C++17)

Returns a pointer to the underlying character array. The pointer is such that the range [data(); data() + size()) is valid and the values in it correspond to the values of the view.

Contents

[edit] Parameters

(none)

[edit] Return value

A pointer to the underlying character array.

[edit] Exceptions

noexcept specification:  
noexcept
  

[edit] Complexity

Constant.

[edit] Notes

Unlike std::basic_string::data() and string literals, data() may return a pointer to a buffer that is not null-terminated. Therefore it is typically a mistake to pass data() to a routine that takes just a const CharT* and expects a null-terminated string.

[edit] Example

#include <iostream>
#include <cstring>
#include <cwchar>
#include <string>
#include <string_view>
int main()
{
    std::wstring_view wcstr_v = L"xyzzy";
    std::cout << std::wcslen(wcstr_v.data()) << '\n';
    // OK: the underlying character array is null-terminated
 
    char array[3] = {'B', 'a', 'r'};
    std::string_view array_v(array, sizeof array);
    // std::cout << std::strlen(array_v.data()) << '\n';
    // error: the underlying character array is not null-terminated
 
    std::string str(array_v.data(), array_v.size()); // OK
    std::cout << std::strlen(str.data()) << '\n';
    // OK: the underlying character array of a std::string is always null-terminated
}

Output:

5
3

[edit] See also

accesses the first character
(public member function) [edit]
accesses the last character
(public member function) [edit]