Namespaces
Variants

    cpp/string/basic string view/data: Difference between revisions

    From cppreference.com
    ← Older edit
    Space Mission (talk | contribs)
    19,873 edits
    m fmt
    Andreas Krug (talk | contribs)
    8,213 edits
    m {{range}}, headers sorted
     
    Line 7: Line 7:
    {{dcl end}}
    {{dcl end}}


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


    ===Parameters===
    ===Parameters===
    Line 24: Line 24:
    {{example
    {{example
    |code=
    |code=
    #include <iostream>
    #include <cstring>
    #include <cstring>
    #include <cwchar>
    #include <cwchar>
    #include <string>
    #include <string>
    #include <string_view>
    #include <string_view>
    int main()
    int main()
    {
    {
    Line 48: Line 49:
    3
    3
    }}
    }}
    ===See also===
    ===See also===
    {{dsc begin}}
    {{dsc begin}}
    {{dsc inc|cpp/string/basic_string_view/dsc front }}
    {{dsc inc|cpp/string/basic_string_view/dsc front}}
    {{dsc inc|cpp/string/basic_string_view/dsc back }}
    {{dsc inc|cpp/string/basic_string_view/dsc back}}
    {{dsc inc|cpp/string/basic_string/dsc {{SUBPAGENAMEE}}}}
    {{dsc inc|cpp/string/basic_string/dsc {{SUBPAGENAMEE}}}}
    {{dsc end}}
    {{dsc end}}


    {{langlinks|es|ja|zh}}
    {{langlinks|es|ja|zh}}

    Latest revision as of 15:05, 4 June 2023

     
    C++
     
    Strings library
     
    std::basic_string_view
     
    constexpr const_pointer data() const noexcept;
    		(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.

    Parameters

    (none)

    Return value

    A pointer to the underlying character array.

    Complexity

    Constant.

    Notes

    Unlike std::basic_string::data() and string literals, std::basic_string_view::data() returns a pointer to a buffer that is not necessarily null-terminated, for example a substring view (e.g. from remove_suffix). Therefore, it is typically a mistake to pass data() to a routine that takes just a const CharT* and expects a null-terminated string.

    Example

    Run this code
    #include <cstring>
#include <cwchar>
#include <iostream>
#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

    See also

    		 accesses the first character
    (public member function) [edit]
    		accesses the last character
    (public member function) [edit]
    		returns a pointer to the first character of a string
    (public member function of std::basic_string<CharT,Traits,Allocator>) [edit]