std::stof, std::stod, std::stold

 

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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

Search basic_string::find basic_string::rfind basic_string::find_first_of basic_string::find_first_not_of basic_string::find_last_of basic_string::find_last_not_of Operations basic_string::compare basic_string::starts_with (C++20) basic_string::ends_with (C++20) basic_string::contains (C++23) basic_string::substr Constants basic_string::npos Non-member functions operator+ swap(std::basic_string) erase(std::basic_string)erase_if(std::basic_string) (C++20)(C++20) I/O operator<<operator>> getline Comparison operator==operator!=operator<operator>operator<=operator>=operator<=> (until C++20)(until C++20)(until C++20)(until C++20)(until C++20)(C++20) Numeric conversions stoistolstoll (C++11)(C++11)(C++11) stoulstoull (C++11)(C++11) stofstodstold (C++11)(C++11)(C++11) to_string (C++11) to_wstring (C++11) Literals operator""s (C++14) Helper classes hash<std::basic_string> (C++11) Deduction guides (C++17)

 

Defined in header <string>
float       stof( const std::string& str, std::size_t* pos = 0 ); float       stof( const std::wstring& str, std::size_t* pos = 0 );	(1)	(since C++11)
double      stod( const std::string& str, std::size_t* pos = 0 ); double      stod( const std::wstring& str, std::size_t* pos = 0 );	(2)	(since C++11)
long double stold( const std::string& str, std::size_t* pos = 0 ); long double stold( const std::wstring& str, std::size_t* pos = 0 );	(3)	(since C++11)

Interprets a floating point value in a string str.

1) calls std::strtod(str.c_str(), &ptr) or std::wcstod(str.c_str(), &ptr)

2) calls std::strtod(str.c_str(), &ptr) or std::wcstod(str.c_str(), &ptr)

3) calls std::strtold(str.c_str(), &ptr) or std::wcstold(str.c_str(), &ptr)

Function discards any whitespace characters (as determined by std::isspace) until first non-whitespace character is found. Then it takes as many characters as possible to form a valid floating-point representation and converts them to a floating-point value. The valid floating-point value can be one of the following:

• decimal floating-point expression. It consists of the following parts:

• (optional) plus or minus sign
• nonempty sequence of decimal digits optionally containing decimal-point character (as determined by the current C locale) (defines significand)
• (optional) e or E followed with optional minus or plus sign and nonempty sequence of decimal digits (defines exponent to base 10)

• hexadecimal floating-point expression. It consists of the following parts:

• (optional) plus or minus sign
• 0x or 0X
• nonempty sequence of hexadecimal digits optionally containing a decimal-point character (as determined by the current C locale) (defines significand)
• (optional) p or P followed with optional minus or plus sign and nonempty sequence of decimal digits (defines exponent to base 2)

• infinity expression. It consists of the following parts:

• (optional) plus or minus sign
• INF or INFINITY ignoring case

• not-a-number expression. It consists of the following parts:

• (optional) plus or minus sign
• NAN or NAN(char_sequence) ignoring case of the NAN part. char_sequence can only contain digits, Latin letters, and underscores. The result is a quiet NaN floating-point value.

• any other expression that may be accepted by the currently installed C locale

If pos is passed a value other than 0 or nullptr, then a pointer ptr, internal to the conversion functions, will receive the address of the first unconverted character, and the index of that character will be calculated and stored in *pos.

Parameters

str	-	the string to convert
pos	-	address of integer to store the index of the first unconverted character

Return value

The string converted to the specified floating point 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 (strtod or strtold) sets errno to ERANGE.

See also

stoistolstoll (C++11)(C++11)(C++11)	converts a string to a signed integer (function)
stoulstoull (C++11)(C++11)	converts a string to an unsigned integer (function)