c/io/fwscanf

Reads data from the a variety of sources, interprets it according to and stores the results into given locations.

@1@ Reads the data from stdin. @2@ Reads the data from file stream. @3@ Reads the data from null-terminated wide string. Reaching the end of the string is equivalent to reaching the end-of-file condition for @4-6@ Same as, except that , , and conversion specifiers each expect two arguments (the usual pointer and a value of type rsize_t indicating the size of the receiving array, which may be  when reading with a  into a single wide character) and except that the following errors are detected at runtime and call the currently installed constraint handler function:
 * any of the arguments of pointer type is a null pointer
 * ,, or is a null pointer
 * the number of characters that would be written by, , or , plus the terminating null character, would exceed the second argument provided for each of those conversion specifiers
 * optionally, any other detectable error, such as unknown conversion specifier
 * As all bounds-checked functions,, , and are only guaranteed to be available if  is defined by the implementation and if the user defines  to the integer constant  before including.

Return value
@1-3@ Number of receiving arguments successfully assigned, or eof if read failure occurs before the first receiving argument was assigned. @4-6@ Same as, except that eof is also returned if there is a runtime constraint violation.