std::string_view find() method

since C++17

// (1) Const version only
constexpr size_type find( basic_string_view v, size_type pos = 0 ) const noexcept;

// (2) Const version only
constexpr size_type find( CharT ch, size_type pos = 0 ) const noexcept;

// (3) Const version only
constexpr size_type find( const CharT* s, size_type pos, size_type count ) const;

// (4) Const version only
constexpr size_type find( const CharT* s, size_type pos = 0 ) const;

Finds the first substring equal to the given character sequence.

• (1) Finds the first occurence of v in this view, starting at position pos.
• (2) Equivalent to find(basic_string_view(std::addressof(ch), 1), pos).
• (3) Equivalent to find(basic_string_view(s, count), pos).
• (4) Equivalent to find(basic_string_view(s), pos).

Parameters

• v - view to search for
• pos - position at which to start the search
• count - length of substring to search for
• s - pointer to a character string to search for
• ch - character to search for

Return value

Position of the first character of the found substring, or npos if no such substring is found.

Complexity

O(size() * v.size()) at worst.

important

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Exceptions

(none)

Example

#include <string_view>
 
int main()
{
    using namespace std::literals;
 
    constexpr auto str{" long long int;"sv};
 
    static_assert(
        1 == str.find("long"sv)            && "<- find(v , pos = 0)" &&
        6 == str.find("long"sv, 2)         && "<- find(v , pos = 2)" &&
        0 == str.find(' ')                 && "<- find(ch, pos = 0)" &&
        2 == str.find('o', 1)              && "<- find(ch, pos = 1)" &&
        2 == str.find("on")                && "<- find(s , pos = 0)" &&
        6 == str.find("long double", 5, 4) && "<- find(s , pos = 5, count = 4)"
    );
 
    static_assert(str.npos == str.find("float"));
}