constexpr int compare(basic_string_view v) const;  (1)  (since C++17) 
constexpr int compare(size_type pos1, size_type count1, basic_string_view v) const;  (2)  (since C++17) 
constexpr int compare(size_type pos1, size_type count1, basic_string_view v, size_type pos2, size_type count2) const;  (3)  (since C++17) 
constexpr int compare(const CharT* s) const;  (4)  (since C++17) 
constexpr int compare(size_type pos1, size_type count1, const CharT* s) const;  (5)  (since C++17) 
constexpr int compare(size_type pos1, size_type count1, const CharT* s, size_type count2) const;  (6)  (since C++17) 
Compares two character sequences.
rlen
of the sequences to compare is the smaller of size()
and v.size()
. The function compares the two views by calling traits::compare(data(), v.data(), rlen)
, and returns a value according to the following table:Condition  Result  Return value  

Traits::compare(data(), v.data(), rlen) < 0  this is less than v  <0 

Traits::compare(data(), v.data(), rlen) == 0  size() < v.size()  this is less than v  <0 
size() == v.size()  this is equal to v  0 

size() > v.size()  this is greater than v  >0 

Traits::compare(data(), v.data(), rlen) > 0  this is greater than v  >0 
substr(pos1, count1).compare(v)
.substr(pos1, count1).compare(v.substr(pos2, count2))
.compare(basic_string_view(s))
.substr(pos1, count1).compare(basic_string_view(s))
.substr(pos1, count1).compare(basic_string_view(s, count2))
.v    view to compare 
s    pointer to the character string to compare to 
count1    number of characters of this view to compare 
pos1    position of the first character in this view to compare 
count2    number of characters of the given view to compare 
pos2    position of the first character of the given view to compare 
negative value if this view is less than the other character sequence, zero if the both character sequences are equal, positive value if this view is greater than the other character sequence.
noexcept
specification: noexcept
1) Linear in the number of characters compared.
lexicographically compares two string views (function template) 
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