std::stoul, std::stoull

 

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std::basic_string

Member functions basic_string::basic_string basic_string::~basic_string basic_string::operator= basic_string::assign basic_string::assign_range (C++23) basic_string::get_allocator Element access basic_string::at basic_string::operator[] basic_string::front (DR*) basic_string::back (DR*) basic_string::data basic_string::c_str basic_string::operator  basic_string_view (C++17) Iterators basic_string::beginbasic_string::cbegin (C++11) basic_string::endbasic_string::cend (C++11) basic_string::rbeginbasic_string::crbegin (C++11) basic_string::rendbasic_string::crend (C++11) Capacity basic_string::empty basic_string::sizebasic_string::length basic_string::max_size basic_string::reserve basic_string::capacity basic_string::shrink_to_fit (DR*) Modifiers basic_string::clear basic_string::insert basic_string::insert_range (C++23) basic_string::erase basic_string::push_back basic_string::pop_back (DR*) basic_string::append basic_string::append_range (C++23) basic_string::operator+= basic_string::replace basic_string::replace_with_range (C++23) basic_string::copy basic_string::resize basic_string::resize_and_overwrite (C++23)   basic_string::swap

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Defined in header <string>
unsigned long      stoul ( const std::string& str,                            std::size_t* pos = nullptr, int base = 10 );	(1)	(since C++11)
unsigned long      stoul ( const std::wstring& str,                            std::size_t* pos = nullptr, int base = 10 );	(2)	(since C++11)
unsigned long long stoull( const std::string& str,                            std::size_t* pos = nullptr, int base = 10 );	(3)	(since C++11)
unsigned long long stoull( const std::wstring& str,                            std::size_t* pos = nullptr, int base = 10 );	(4)	(since C++11)

Interprets an unsigned integer value in the string str.

Let ptr be an internal (to the conversion functions) pointer of type char* (1,3) or wchar_t* (2,4), accordingly.

1) Calls std::strtoul(str.c_str(), &ptr, base).

2) Calls std::wcstoul(str.c_str(), &ptr, base).

3) Calls std::strtoull(str.c_str(), &ptr, base).

4) Calls std::wcstoull(str.c_str(), &ptr, base).

Discards any whitespace characters (as identified by calling std::isspace) until the first non-whitespace character is found, then takes as many characters as possible to form a valid base-n (where n=base) unsigned integer number representation and converts them to an integer value. The valid unsigned integer value consists of the following parts:

• (optional) plus or minus sign
• (optional) prefix (0) indicating octal base (applies only when the base is 8 or ​0​)
• (optional) prefix (0x or 0X) indicating hexadecimal base (applies only when the base is 16 or ​0​)
• a sequence of digits

The set of valid values for base is {0,2,3,...,36}. The set of valid digits for base-2 integers is {0,1}, for base-3 integers is {0,1,2}, and so on. For bases larger than 10, valid digits include alphabetic characters, starting from Aa for base-11 integer, to Zz for base-36 integer. The case of the characters is ignored.

Additional numeric formats may be accepted by the currently installed C locale.

If the value of base is ​0​, the numeric base is auto-detected: if the prefix is 0, the base is octal, if the prefix is 0x or 0X, the base is hexadecimal, otherwise the base is decimal.

If the minus sign was part of the input sequence, the numeric value calculated from the sequence of digits is negated as if by unary minus in the result type, which applies unsigned integer wraparound rules.

If pos is not a null pointer, then ptr will receive the address of the first unconverted character in str.c_str(), and the index of that character will be calculated and stored in *pos, giving the number of characters that were processed by the conversion.

Parameters

str	-	the string to convert
pos	-	address of an integer to store the number of characters processed
base	-	the number base

Return value

The string converted to the specified unsigned integer type.

Exceptions

• std::invalid_argument if no conversion could be performed.
• std::out_of_range if the converted value would fall out of the range of the result type or if the underlying function (std::strtoul or std::strtoull) sets errno to ERANGE.

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR	Applied to	Behavior as published	Correct behavior
LWG 2009	C++11	std::out_of_range would not be thrown if std::strtoul or std::strtoull sets errno to ERANGE	will throw

See also

stoistolstoll (C++11)(C++11)(C++11)	converts a string to a signed integer (function)
stofstodstold (C++11)(C++11)(C++11)	converts a string to a floating point value (function)