std::stoul, std::stoull

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)

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

(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

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

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

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

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

Example

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

Compiler support
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Language
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Feature test macros (C++20)
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External libraries

Classes
basic_string
basic_string_view (C++17)
char_traits

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)