Functions for number conversion and formatted string output.
PyOS_snprintf() and PyOS_vsnprintf() wrap the Standard C library functions snprintf() and vsnprintf(). Their purpose is to guarantee consistent behavior in corner cases, which the Standard C functions do not.
The wrappers ensure that str*[*size-1] is always '\0' upon return. They never write more than size bytes (including the trailing '\0') into str. Both functions require that str != NULL, size > 0 and format != NULL.
If the platform doesn’t have vsnprintf() and the buffer size needed to avoid truncation exceeds size by more than 512 bytes, Python aborts with a Py_FatalError.
The return value (rv) for these functions should be interpreted as follows:
The following functions provide locale-independent string to number conversions.
Convert a string to a double. This function behaves like the Standard C function strtod() does in the C locale. It does this without changing the current locale, since that would not be thread-safe.
PyOS_ascii_strtod() should typically be used for reading configuration files or other non-user input that should be locale independent.
See the Unix man page strtod(2) for details.
Deprecated since version 3.1: Use PyOS_string_to_double() instead.
Convert a string s to a double, raising a Python exception on failure. The set of accepted strings corresponds to the set of strings accepted by Python’s float() constructor, except that s must not have leading or trailing whitespace. The conversion is independent of the current locale.
If endptr is NULL, convert the whole string. Raise ValueError and return -1.0 if the string is not a valid representation of a floating-point number.
If endptr is not NULL, convert as much of the string as possible and set *endptr to point to the first unconverted character. If no initial segment of the string is the valid representation of a floating-point number, set *endptr to point to the beginning of the string, raise ValueError, and return -1.0.
If s represents a value that is too large to store in a float (for example, "1e500" is such a string on many platforms) then if overflow_exception is NULL return Py_HUGE_VAL (with an appropriate sign) and don’t set any exception. Otherwise, overflow_exception must point to a Python exception object; raise that exception and return -1.0. In both cases, set *endptr to point to the first character after the converted value.
If any other error occurs during the conversion (for example an out-of-memory error), set the appropriate Python exception and return -1.0.
New in version 3.1.
Convert a double to a string using the '.' as the decimal separator. format is a printf()-style format string specifying the number format. Allowed conversion characters are 'e', 'E', 'f', 'F', 'g' and 'G'.
The return value is a pointer to buffer with the converted string or NULL if the conversion failed.
Deprecated since version 3.1: Use PyOS_double_to_string() instead.
Convert a double val to a string using supplied format_code, precision, and flags.
format_code must be one of 'e', 'E', 'f', 'F', 'g', 'G' or 'r'. For 'r', the supplied precision must be 0 and is ignored. The 'r' format code specifies the standard repr() format.
flags can be zero or more of the values Py_DTSF_SIGN, Py_DTSF_ADD_DOT_0, or Py_DTSF_ALT, or-ed together:
If ptype is non-NULL, then the value it points to will be set to one of Py_DTST_FINITE, Py_DTST_INFINITE, or Py_DTST_NAN, signifying that val is a finite number, an infinite number, or not a number, respectively.
The return value is a pointer to buffer with the converted string or NULL if the conversion failed. The caller is responsible for freeing the returned string by calling PyMem_Free().
New in version 3.1.
Convert a string to a double in a locale-independent way.
See the Unix man page atof(2) for details.
Deprecated since version 3.1: Use PyOS_string_to_double() instead.