Functions for number conversion and formatted string output.
|char *str, size_t size, const char *format, ...)|
|char *str, size_t size, const char *format, va_list va)|
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:
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.
|const char *nptr, char **endptr)|
PyOS_ascii_strtod should typically be used for reading configuration files or other non-user input that should be locale independent. New in version 2.4.
See the Unix man page strtod(2) for details.
|char *buffer, size_t buf_len, const char *format, double d)|
The return value is a pointer to buffer with the converted string or NULL if the conversion failed. New in version 2.4.
|const char *nptr)|
See the Unix man page atof(2) for details.