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6.6 Input and Output Functions

When using any of these functions, it's a good idea to include stdio.h before gmp.h, since that will allow gmp.h to define prototypes for these functions.

Passing a NULL pointer for a stream argument to any of these functions will make them read from stdin and write to stdout, respectively.

— Function: size_t mpq_out_str (FILE *stream, int base, mpq_t op)

Output op on stdio stream stream, as a string of digits in base base. The base may vary from 2 to 36. Output is in the form `num/den' or if the denominator is 1 then just `num'.

Return the number of bytes written, or if an error occurred, return 0.

— Function: size_t mpq_inp_str (mpq_t rop, FILE *stream, int base)

Read a string of digits from stream and convert them to a rational in rop. Any initial white-space characters are read and discarded. Return the number of characters read (including white space), or 0 if a rational could not be read.

The input can be a fraction like `17/63' or just an integer like `123'. Reading stops at the first character not in this form, and white space is not permitted within the string. If the input might not be in canonical form, then mpq_canonicalize must be called (see Rational Number Functions).

The base can be between 2 and 36, or can be 0 in which case the leading characters of the string determine the base, `0x' or `0X' for hexadecimal, `0' for octal, or decimal otherwise. The leading characters are examined separately for the numerator and denominator of a fraction, so for instance `0x10/11' is 16/11, whereas `0x10/0x11' is 16/17.