Read and interpret text from standard output stream
int scanf(const char *format[, arg, ...]);
The number of input fields for which scanning, conversion, and storage were executed normally is returned. The return value does not include scanned fields that were not stored. If an attempt is made to read to the end of the file, the return value is EOF. If no field was stored, the return value is 0.
Reads the input to be converted according to the format specified by the character string pointed to by format from the standard input/output stdin and treats the arg arguments that follow format as objects for storing the converted input. The method of specifying format is the same as described for the sscanf function.