Edit File: conversion.txt
.. highlightlang:: c .. _string-conversion: String conversion and formatting ================================ Functions for number conversion and formatted string output. .. cfunction:: 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 :manpage:`snprintf(2)`. .. cfunction:: 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 :manpage:`vsnprintf(2)`. :cfunc:`PyOS_snprintf` and :cfunc:`PyOS_vsnprintf` wrap the Standard C library functions :cfunc:`snprintf` and :cfunc:`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 :cfunc:`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 with ``rv + 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. .. cfunction:: double PyOS_ascii_strtod(const char *nptr, char **endptr) Convert a string to a :ctype:`double`. This function behaves like the Standard C function :cfunc:`strtod` does in the C locale. It does this without changing the current locale, since that would not be thread-safe. :cfunc:`PyOS_ascii_strtod` should typically be used for reading configuration files or other non-user input that should be locale independent. .. versionadded:: 2.4 See the Unix man page :manpage:`strtod(2)` for details. .. cfunction:: char * PyOS_ascii_formatd(char *buffer, size_t buf_len, const char *format, double d) Convert a :ctype:`double` to a string using the ``'.'`` as the decimal separator. *format* is a :cfunc:`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. .. versionadded:: 2.4 .. cfunction:: double PyOS_ascii_atof(const char *nptr) Convert a string to a :ctype:`double` in a locale-independent way. .. versionadded:: 2.4 See the Unix man page :manpage:`atof(2)` for details. .. cfunction:: char * PyOS_stricmp(char *s1, char *s2) Case insensitive comparison of strings. The function works almost identically to :cfunc:`strcmp` except that it ignores the case. .. versionadded:: 2.6 .. cfunction:: char * PyOS_strnicmp(char *s1, char *s2, Py_ssize_t size) Case insensitive comparison of strings. The function works almost identically to :cfunc:`strncmp` except that it ignores the case. .. versionadded:: 2.6
Back to File Manager