Functions for number conversion and formatted string output.
PyOS_snprintf(char *str, size_t size, const char *format, ...)
PyOS_vsnprintf(char *str, size_t size, const char *format, va_list va)
PyOS_vsnprintf() wrap the Standard C library
vsnprintf(). Their purpose is to
guarantee consistent behavior in corner cases, which the Standard C functions do
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
The return value (rv) for these functions should be interpreted as follows:
0 <= rv < size, the output conversion was successful and rv characters were written to str (excluding the trailing
'\0'byte at str*[*rv]).
rv >= size, the output conversion was truncated and a buffer with
rv + 1bytes would have been needed to succeed. str*[*size-1] is
'\0'in this case.
rv < 0, “something bad happened.” str*[*size-1] is
'\0'in this case too, but the rest of str is undefined. The exact cause of the error depends on the underlying platform.
The following functions provide locale-independent string to number conversions.
PyOS_string_to_double(const char *s, char **endptr, PyObject *overflow_exception)
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
s must not have leading or trailing whitespace.
The conversion is independent of the current locale.
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
s represents a value that is too large to store in a float
"1e500" is such a string on many platforms) then
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
New in version 3.1.
PyOS_double_to_string(double val, char format_code, int precision, int flags, int *ptype)
double val to a string using supplied
format_code, precision, and flags.
format_code must be one of
'r', the supplied precision
must be 0 and is ignored. The
'r' format code specifies the
flags can be zero or more of the values
Py_DTSF_ALT, or-ed together:
Py_DTSF_SIGN means to always precede the returned string with a sign
character, even if val is non-negative.
Py_DTSF_ADD_DOT_0 means to ensure that the returned string will not look
like an integer.
Py_DTSF_ALT means to apply “alternate” formatting rules. See the
documentation for the
'#' specifier for
If ptype is non-
NULL, then the value it points to will be set to one of
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
New in version 3.1.
PyOS_stricmp(const char *s1, const char *s2)
strcmp()except that it ignores the case.
PyOS_strnicmp(const char *s1, const char *s2, Py_ssize_t size)
strncmp()except that it ignores the case.