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std::basic_string<CharT,Traits,Allocator>::compare - cppreference.com
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      std::basic_string<CharT,Traits,Allocator>::compare

      : cppreference.com
       
      C++
      (C++20)
      (C++20)
      (C++17)
      (C++11)
      (C++11)
      (C++11)
       
       
      std::basic_string
       
      <tbody> </tbody> <tbody class="t-dcl-rev t-dcl-rev-num "> </tbody><tbody> </tbody> <tbody class="t-dcl-rev t-dcl-rev-num "> </tbody><tbody> </tbody> <tbody class="t-dcl-rev t-dcl-rev-num "> </tbody><tbody> </tbody> <tbody class="t-dcl-rev t-dcl-rev-num "> </tbody><tbody> </tbody> <tbody class="t-dcl-rev t-dcl-rev-num "> </tbody><tbody> </tbody> <tbody class="t-dcl-rev t-dcl-rev-num "> </tbody><tbody> </tbody> <tbody class="t-dcl-rev t-dcl-rev-num "> </tbody><tbody> </tbody> <tbody class="t-dcl-rev t-dcl-rev-num "> </tbody><tbody> </tbody> <tbody class="t-dcl-rev t-dcl-rev-num "> </tbody><tbody> </tbody>
      (1)
      int compare( const basic_string& str ) const;
      		 (C++11)
      int compare( const basic_string& str ) const noexcept;
      		 (C++11)
      (C++20)
      constexpr int compare( const basic_string& str ) const noexcept;
      		 (C++20)
      (2)
      int compare( size_type pos1, size_type count1, const basic_string& str ) const;
      		 (C++20)
      constexpr int compare( size_type pos1, size_type count1, const basic_string& str ) const;
      		 (C++20)
      (3)
      int compare( size_type pos1, size_type count1, const basic_string& str, size_type pos2, size_type count2 ) const;
      		 (C++14)
      int compare( size_type pos1, size_type count1, const basic_string& str, size_type pos2, size_type count2 = npos ) const;
      		 (C++14)
      (C++20)
      constexpr int compare( size_type pos1, size_type count1, const basic_string& str, size_type pos2, size_type count2 = npos ) const;
      		 (C++20)
      (4)
      int compare( const CharT* s ) const;
      		 (C++20)
      constexpr int compare( const CharT* s ) const;
      		 (C++20)
      (5)
      int compare( size_type pos1, size_type count1, const CharT* s ) const;
      		 (C++20)
      constexpr int compare( size_type pos1, size_type count1, const CharT* s ) const;
      		 (C++20)
      (6)
      int compare( size_type pos1, size_type count1, const CharT* s, size_type count2 ) const;
      		 (C++20)
      constexpr int compare( size_type pos1, size_type count1, const CharT* s, size_type count2 ) const;
      		 (C++20)
      (7)
      template < class T > int compare( const T& t ) const noexcept(/* see below */);
      		 (C++17)
      (C++20)
      template < class T > constexpr int compare( const T& t ) const noexcept(/* see below */);
      		 (C++20)
      (8)
      template < class T > int compare( size_type pos1, size_type count1, const T& t ) const;
      		 (C++17)
      (C++20)
      template < class T > constexpr int compare( size_type pos1, size_type count1, const T& t ) const;
      		 (C++20)
      (9)
      template < class T > int compare( size_type pos1, size_type count1, const T& t, size_type pos2, size_type count2 = npos) const;
      		 (C++17)
      (C++20)
      template < class T > constexpr int compare( size_type pos1, size_type count1, const T& t, size_type pos2, size_type count2 = npos) const;
      		 (C++20)

      2

      1) str
      2) [pos1, pos1+count1) str count1 > size() - pos1 [pos1, size())
      3) [pos1, pos1+count1) str [pos2, pos2+count2) count1 > size() - pos1 1 [pos1, size()) count2 > str.size() - pos2 2 [pos2, str.size())
      4) s Traits::length(s)
      5) [pos1, pos1+count1) s Traits::length(s) count1 > size() - pos1 [pos1, size())
      6) [pos1, pos1+count1) [s, s + count2) If count1 > size() - pos1 the substring is [pos1, size()). (Note: the characters in the range [s, s + count2) may include null characters.)
      7) std::basic_string_view<CharT, Traits> sv = t; t sv sv std::is_convertible_v<const T&, std::basic_string_view<CharT, Traits>> true std::is_convertible_v<const T&, const CharT*> false
      8) std::basic_string_view<CharT, Traits> sv = t; t sv std::basic_string_view<CharT, Traits>(*this).substr(pos1, count1).compare(sv) [pos1, pos1+count1) sv std::is_convertible_v<const T&, std::basic_string_view<CharT, Traits>> true std::is_convertible_v<const T&, const CharT*> false
      9) std::basic_string_view<CharT, Traits> sv = t; t sv std::basic_string_view<CharT, Traits>(*this).substr(pos1, count1).compare(sv.substr(pos2, count2)) [pos1, pos1+count1) sv [pos2, pos2+count2) std::is_convertible_v<const T&, std::basic_string_view<CharT, Traits>> true std::is_convertible_v<const T&, const CharT*> false

      data1 count1 data2 count2 size_type rlen = std::min(count1, count2) Traits::compare(data1, data2, rlen) ()

      Traits::compare(data1, data2, rlen) < 0 data1 data2 <0
      Traits::compare(data1, data2, rlen) == 0 size1 < size2 data1 data2 <0
      size1 == size2 data1 data2 0
      size1 > size2 data1 data2 >0
      Traits::compare(data1, data2, rlen) > 0 data1 data2 >0

      str -
      s -
      count1 -
      pos1 -
      count2 -
      pos2 -
      t - (std::basic_string_view )

      *this

      *this

      pos1 pos2 std::out_of_range

      7)
      noexcept :  
      noexcept(std::is_nothrow_convertible_v<const T&, std::basic_string_view<CharT, Traits>>)
      8-9) basic_string_view

      C++

      DR
      LWG 2946 C++17 string_view overload causes ambiguity in some cases avoided by making it a template 

      template<class CharT, class Traits, class Alloc>
int basic_string<CharT, Traits, Alloc>::compare(const std::basic_string& s) const noexcept
{
    size_type lhs_sz = size();
    size_type rhs_sz = s.size();
    int result = traits_type::compare(data(), s.data(), std::min(lhs_sz, rhs_sz));
    if (result != 0)
        return result;
    if (lhs_sz < rhs_sz)
        return -1;
    if (lhs_sz > rhs_sz)
        return 1;
    return 0;
}

      std::basic_string (<, <=, ==, > )

      ( std::char_traits ) std::collate::compare

      Run this code
      #include <cassert>
#include <string>
#include <iostream>
 
int main() 
{
    // 1) 
    {
        int compare_value{
            std::string{"Batman"}.compare(std::string{"Superman"})
        };
        std::cout << (
            compare_value < 0 ? "Batman comes before Superman\n" :
            compare_value > 0 ? "Superman comes before Batman\n" :
            "Superman and Batman are the same.\n"
        );
    }
    
    // 2) 
    {
        int compare_value{
            std::string{"Batman"}.compare(3, 3, std::string{"Superman"})
        };
        std::cout << (
            compare_value < 0 ? "man comes before Superman\n" :
            compare_value > 0 ? "Superman comes before man\n" :
            "man and Superman are the same.\n"
        );
    }
    
    // 3) 
    {
        std::string a{"Batman"};
        std::string b{"Superman"};
        
        int compare_value{a.compare(3, 3, b, 5, 3)};
        
        std::cout << (
            compare_value < 0 ? "man comes before man\n" :
            compare_value > 0 ? "man comes before man\n" :
            "man and man are the same.\n"
        );
        // 
        //  () 
        assert(compare_value == a.compare(3, 3, b, 5));
    }
    
    // 4) char 
    {
        int compare_value{std::string{"Batman"}.compare("Superman")};
        
        std::cout << (
            compare_value < 0 ? "Batman comes before Superman\n" :
            compare_value > 0 ? "Superman comes before Batman\n" :
            "Superman and Batman are the same.\n"
        );
    }
    
    // 5)  char 
    {
        int compare_value{std::string{"Batman"}.compare(3, 3, "Superman")};
        
        std::cout << (
            compare_value < 0 ? "man comes before Superman\n" :
            compare_value > 0 ? "Superman comes before man\n" :
            "man and Superman are the same.\n"
        );
    }
    
    // 6)  char 
    {
        int compare_value{std::string{"Batman"}.compare(0, 3, "Superman", 5)};
        
        std::cout << (
            compare_value < 0 ? "Bat comes before Super\n" :
            compare_value > 0 ? "Super comes before Bat\n" :
            "Super and Bat are the same.\n"
        );
    }
}

      : 

      Batman comes before Superman
Superman comes before man
man and man are the same.
Batman comes before Superman
Superman comes before man
Bat comes before Super

      (C++20)(C++20)(C++20)(C++20)(C++20)(C++20)
      		 2
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      () [edit]

      () [edit]
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