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std::wcstof, std::wcstod, std::wcstold

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< cpp‎ | string‎ | wide
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Defined in header <cwchar>
float       wcstof( const wchar_t* str, wchar_t** str_end );
(since C++11)
double      wcstod( const wchar_t* str, wchar_t** str_end );
long double wcstold( const wchar_t* str, wchar_t** str_end );
(since C++11)

Interprets a floating point value in a wide string pointed to by str.

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 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)
  • binary 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)
  • 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 alphanumeric characters. The result is a quiet NaN floating point value.
  • any other expression that may be accepted by the currently installed C locale

The functions sets the pointer pointed to by str_end to point to the wide character past the last character interpreted. If str_end is NULL, it is ignored.

Contents

[edit] Parameters

str - pointer to the null-terminated wide string to be interpreted
str_end - pointer to a pointer to a wide character.

[edit] Return value

Floating point value corresponding to the contents of str on success. If the converted value falls out of range of corresponding return type, range error occurs and HUGE_VAL, HUGE_VALF or HUGE_VALL is returned. If no conversion can be performed, 0 is returned.

[edit] Example

[edit] See also

C documentation for wcstof