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

From cppreference.com
< cpp‎ | string‎ | wide

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.

### [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

| This section is incomplete Reason: no example

### [edit] See also

C documentation for wcstof

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- Todo no example