Functions for number conversion and formatted string output.
int PyOS_snprintf(char *str, size_t size, const char *format, ...)
Output not more than size bytes to str according to the format string format and the extra arguments. See the Unix man page [UNKNOWN NODE manpage].
int PyOS_vsnprintf(char *str, size_t size, const char *format, va_list va)
Output not more than size bytes to str according to the format string format and the variable argument list va. Unix man page [UNKNOWN NODE manpage].
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:
- When
0 <= rv < size, the output conversion was successful and rv characters were written to str (excluding the trailing'\0'byte at str*[*rv]). - When
rv >= size, the output conversion was truncated and a buffer withrv + 1bytes would have been needed to succeed. str*[*size-1] is'\0'in this case. - When
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.
double 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 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 2.7.
double PyOS_ascii_strtod(const char *nptr, char **endptr)
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 [UNKNOWN NODE manpage] for details.
New in version 2.4.
Deprecated since version 2.7: Use PyOS_string_to_double() instead.
char* PyOS_ascii_formatd(char *buffer, size_t buf_len, const char *format, double d)
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.
New in version 2.4.
Deprecated since version 2.7: This function is removed in Python 2.7 and 3.1. Use PyOS_double_to_string()
instead.
char* PyOS_double_to_string(double val, char format_code, int precision, int flags, int *ptype)
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:
- 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
PyOS_snprintf()'#'specifier for details.
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 2.7.
double PyOS_ascii_atof(const char *nptr)
Convert a string to a double in a locale-independent way.
See the Unix man page [UNKNOWN NODE manpage] for details.
New in version 2.4.
Deprecated since version 3.1: Use PyOS_string_to_double() instead.
char* PyOS_stricmp(char *s1, char *s2)
Case insensitive comparison of strings. The function works almost
identically to strcmp() except that it ignores the case.
New in version 2.6.
char* PyOS_strnicmp(char *s1, char *s2, Py_ssize_t size)
Case insensitive comparison of strings. The function works almost
identically to strncmp() except that it ignores the case.
New in version 2.6.