23 Strings library [strings]

23.3 String view classes [string.view]

23.3.3 Class template basic_string_view [string.view.template]

23.3.3.8 String operations [string.view.ops]

constexpr size_type copy(charT* s, size_type n, size_type pos = 0) const;

Let rlen be the smaller of n and size() - pos.

Preconditions: [s, s + rlen) is a valid range.

Effects: Equivalent to traits::copy(s, data() + pos, rlen).

Returns: rlen.

Throws: out_of_range if pos > size().

Complexity:

O (rlen)

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constexpr basic_string_view substr(size_type pos = 0, size_type n = npos) const;

Let rlen be the smaller of n and size() - pos.

Effects: Determines rlen, the effective length of the string to reference.

Returns: basic_string_view(data() + pos, rlen).

Throws: out_of_range if pos > size().

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constexpr int compare(basic_string_view str) const noexcept;

Let rlen be the smaller of size() and str.size().

Effects: Determines rlen, the effective length of the strings to compare.

The function then compares the two strings by calling traits::compare(data(), str.data(), rlen).

Returns: The nonzero result if the result of the comparison is nonzero.

Otherwise, returns a value as indicated in Table 80 .

Table 80: compare() results [tab:string.view.compare]

🔗	Condition	Return Value
🔗	size() < str.size()	< 0
🔗	size() == str.size()	0
🔗	size() > str.size()	> 0

Complexity:

O (rlen)

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constexpr int compare(size_type pos1, size_type n1, basic_string_view str) const;

Effects: Equivalent to: return substr(pos1, n1).compare(str);

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constexpr int compare(size_type pos1, size_type n1, basic_string_view str,
                      size_type pos2, size_type n2) const;

Effects: Equivalent to: return substr(pos1, n1).compare(str.substr(pos2, n2));

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constexpr int compare(const charT* s) const;

Effects: Equivalent to: return compare(basic_string_view(s));

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constexpr int compare(size_type pos1, size_type n1, const charT* s) const;

Effects: Equivalent to: return substr(pos1, n1).compare(basic_string_view(s));

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constexpr int compare(size_type pos1, size_type n1, const charT* s, size_type n2) const;

Effects: Equivalent to: return substr(pos1, n1).compare(basic_string_view(s, n2));

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constexpr bool starts_with(basic_string_view x) const noexcept;

Effects: Equivalent to: return substr(0, x.size()) == x;

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constexpr bool starts_with(charT x) const noexcept;

Effects: Equivalent to: return !empty() && traits::eq(front(), x);

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constexpr bool starts_with(const charT* x) const;

Effects: Equivalent to: return starts_with(basic_string_view(x));

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constexpr bool ends_with(basic_string_view x) const noexcept;

Effects: Equivalent to: return size() >= x.size() && compare(size() - x.size(), npos, x) == 0;

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constexpr bool ends_with(charT x) const noexcept;

Effects: Equivalent to: return !empty() && traits::eq(back(), x);

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constexpr bool ends_with(const charT* x) const;

Effects: Equivalent to: return ends_with(basic_string_view(x));

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constexpr bool contains(basic_string_view x) const noexcept;
constexpr bool contains(charT x) const noexcept;
constexpr bool contains(const charT* x) const;

Effects: Equivalent to: return find(x) != npos;