String conversion and formatting (original) (raw)

Functions for number conversion and formatted string output.

int PyOS_snprintf(char *str, size_t size, const char *format, ...)¶

Part of the Stable ABI.

Output not more than size bytes to str according to the format string_format_ and the extra arguments. See the Unix man page snprintf(3).

int PyOS_vsnprintf(char *str, size_t size, const char *format, va_list va)¶

Part of the Stable ABI.

Output not more than size bytes to str according to the format string_format_ and the variable argument list va. Unix man page_vsnprintf(3)_.

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, format != NULLand size < INT_MAX. Note that this means there is no equivalent to the C99n = snprintf(NULL, 0, ...) which would determine the necessary buffer size.

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 atstr[rv]).
• When rv >= size, the output conversion was truncated and a buffer withrv + 1 bytes 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.

unsigned long PyOS_strtoul(const char *str, char **ptr, int base)¶

Part of the Stable ABI.

Convert the initial part of the string in str to an unsigned long value according to the given base, which must be between 2 and36 inclusive, or be the special value 0.

Leading white space and case of characters are ignored. If base is zero it looks for a leading 0b, 0o or 0x to tell which base. If these are absent it defaults to 10. Base must be 0 or between 2 and 36 (inclusive). If ptr is non-NULL it will contain a pointer to the end of the scan.

If the converted value falls out of range of corresponding return type, range error occurs (errno is set to ERANGE) andULONG_MAX is returned. If no conversion can be performed, 0is returned.

See also the Unix man page strtoul(3).

Added in version 3.2.

long PyOS_strtol(const char *str, char **ptr, int base)¶

Part of the Stable ABI.

Convert the initial part of the string in str to an long value according to the given base, which must be between 2 and 36inclusive, or be the special value 0.

Same as PyOS_strtoul(), but return a long value instead and LONG_MAX on overflows.

See also the Unix man page strtol(3).

Added in version 3.2.

double PyOS_string_to_double(const char *s, char **endptr, PyObject *overflow_exception)¶

Part of the Stable ABI.

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. RaiseValueError 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_INFINITY (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.

Added in version 3.1.

char *PyOS_double_to_string(double val, char format_code, int precision, int flags, int *ptype)¶

Part of the Stable ABI.

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 ofPy_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 orNULL if the conversion failed. The caller is responsible for freeing the returned string by calling PyMem_Free().

Added in version 3.1.

int PyOS_stricmp(const char *s1, const char *s2)¶

Case insensitive comparison of strings. The function works almost identically to strcmp() except that it ignores the case.

int PyOS_strnicmp(const char *s1, const char *s2, Py_ssize_t size)¶

Case insensitive comparison of strings. The function works almost identically to strncmp() except that it ignores the case.