Converts a string to a double-precision floating-point.
Standard C Library
The wstrtod subroutine returns a double-precision floating-point number that is converted from an wchar_t string pointed to by the String parameter. The system searches the String until it finds the first unrecognized character.
The wstrtod subroutine recognizes a string that starts with any number of white-space characters (defined by the iswspace subroutine), followed by an optional sign, a string of decimal digits that may include a decimal point, e or E, an optional sign or space, and an integer.
When the value of Pointer is not (wchar_t **) null, a pointer to the search terminating character is returned to the address indicated by Pointer. When the resulting number cannot be created, *Pointer is set to String and 0 (zero) is returned.
The watof (String) subroutine functions like the wstrtod (String (wchar_t **) null).
| Item | Description |
|---|---|
| String | Specifies the address of the string to scan. |
| Pointer | Specifies the address at which the pointer to the terminating character is stored. |
When the value causes overflow, HUGE_VAL (defined in the math.h file) is returned with the appropriate sign, and the errno global variable is set to ERANGE. When the value causes underflow, 0 is returned and the errno global variable is set to ERANGE.