Datasheet

The C and C++ Libraries
4-76 Copyright © 1999-2001 ARM Limited. All rights reserved. ARM DUI 0067D
printf family
The
printf family consists of _printf() , printf() , _fprintf() , fprintf() , vprintf() ,
and
vfprintf() . All these functions use __FILE opaquely and depend only on the
functions
fputc() and ferror() . The functions _printf() and _fprintf() are identical to
printf() and fprintf() except that they cannot format floating-point values.
The standard output functions of the form
_printf(...) are equivalent to:
fprintf(& __stdout, ...)
where __stdout has type __FILE .
scanf family
The
scanf() family consists of scanf() and fscanf() . These functions depend only on
the functions
fgetc() , __FILE , and __backspace() .
The standard input form
scanf(...) is equivalent to:
fscanf(& __stdin, ...)
where __stdin has type __FILE .
fwrite(), fputs, and puts
If you define your own version of
__FILE , and your own fputc() and ferror() functions
and the
__stdout object, you can use all of the printf() family, fwrite() , fputs() , and
puts() unchanged from the library. Example 4-19 shows how to do this. Consider
modifying the system routines if you require real file handling.
Example 4-19 printf() and __FILE
#include <stdio.h>
struct __FILE {
int handle;
/* Whatever you need here (if the only files you are using
is the stdoutput using printf for debugging, no file
handling is required) */
};
FILE __stdout;
int fputc(int ch, FILE *f)
{
/* Your implementation of fputc */
return ch;
}
int ferror(FILE *f)