cppdraft_translate/cppdraft/string/view/find.md

[string.view.find]

27 Strings library [strings]

27.3 String view classes [string.view]

27.3.3 Class template basic_string_view [string.view.template]

27.3.3.9 Searching [string.view.find]

1

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Member functions in this subclause have complexity O(size() * str.size()) at worst, although implementations should do better.

2

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Let F be one offind,rfind,find_first_of,find_last_of,find_first_not_of, andfind_last_not_of.

• (2.1)

Each member function of the formconstexpr return-type F(const charT* s, size_type pos) const; has effects equivalent to: return F(basic_string_view(s), pos);

• (2.2)

Each member function of the formconstexpr return-type F(const charT* s, size_type pos, size_type n) const; has effects equivalent to: return F(basic_string_view(s, n), pos);

• (2.3)

Each member function of the formconstexpr return-type F(charT c, size_type pos) const noexcept; has effects equivalent to: return F(basic_string_view(addressof(c), 1), pos);

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constexpr size_type find(basic_string_view str, size_type pos = 0) const noexcept;

3

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Let xpos be the lowest position, if possible, such that the following conditions hold:

• (3.1)

pos <= xpos

• (3.2)

xpos + str.size() <= size()

• (3.3)

traits​::​eq(data_[xpos + I], str[I]) for all elements I of the string referenced by str.

4

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Effects: Determines xpos.

5

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Returns: xpos if the function can determine such a value for xpos.

Otherwise, returns npos.

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constexpr size_type rfind(basic_string_view str, size_type pos = npos) const noexcept;

6

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Let xpos be the highest position, if possible, such that the following conditions hold:

• (6.1)

xpos <= pos

• (6.2)

xpos + str.size() <= size()

• (6.3)

traits​::​eq(data_[xpos + I], str[I]) for all elements I of the string referenced by str.

7

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Effects: Determines xpos.

8

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Returns: xpos if the function can determine such a value for xpos.

Otherwise, returns npos.

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constexpr size_type find_first_of(basic_string_view str, size_type pos = 0) const noexcept;

9

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Let xpos be the lowest position, if possible, such that the following conditions hold:

• (9.1)

pos <= xpos

• (9.2)

xpos < size()

• (9.3)

traits​::​eq(data_[xpos], str[I]) for some element I of the string referenced by str.

10

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Effects: Determines xpos.

11

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Returns: xpos if the function can determine such a value for xpos.

Otherwise, returns npos.

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constexpr size_type find_last_of(basic_string_view str, size_type pos = npos) const noexcept;

12

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Let xpos be the highest position, if possible, such that the following conditions hold:

• (12.1)

xpos <= pos

• (12.2)

xpos < size()

• (12.3)

traits​::​eq(data_[xpos], str[I]) for some element I of the string referenced by str.

13

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Effects: Determines xpos.

14

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Returns: xpos if the function can determine such a value for xpos.

Otherwise, returns npos.

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constexpr size_type find_first_not_of(basic_string_view str, size_type pos = 0) const noexcept;

15

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Let xpos be the lowest position, if possible, such that the following conditions hold:

• (15.1)

pos <= xpos

• (15.2)

xpos < size()

• (15.3)

traits​::​eq(data_[xpos], str[I]) for no element I of the string referenced by str.

16

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Effects: Determines xpos.

17

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Returns: xpos if the function can determine such a value for xpos.

Otherwise, returns npos.

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constexpr size_type find_last_not_of(basic_string_view str, size_type pos = npos) const noexcept;

18

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Let xpos be the highest position, if possible, such that the following conditions hold:

• (18.1)

xpos <= pos

• (18.2)

xpos < size()

• (18.3)

traits​::​eq(data_[xpos], str[I]) for no element I of the string referenced by str.

19

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Effects: Determines xpos.

20

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Returns: xpos if the function can determine such a value for xpos.

Otherwise, returns npos.