Write text in specified format to standard output stream

[Classification]

Standard library

[Syntax]

#include <stdio.h>

int vprintf(const char *format, va_list arg);

[Return value]

The number of characters that were output is returned.

[Description]

This function applies the format specified by the string pointed to by format to the argument string pointed to by arg, and outputs the formatted data that was output as a result to the standard input/output stdout. The method of specifying format is the same as described for the sprintf function. The vprintf function is equivalent to sprintf with the list of a variable number of real arguments replaced by arg. arg must be initialized by the va_start macro before the vprintf function is called.

[Caution]

Stdout (standard output) and stderr (standard error) are specified for the argument stream. 1 memory addresses such as an I/O address is allocated for the I/O destination of stream. To use these streams in combination with a debugger, the initial values of the stream structure defined in stdio.h must be set. Be sure to set the initial values prior to calling the function.

[Definition of stream structure in stdio.h]

typedef struct {

        int         mode;   /*with error descriptions*/

        unsigend    handle;

        int         unget_c;

} FILE;

typedef int     fpos_t;

extern  FILE*   _REL_stdin();

extern  FILE*   _REL_stdout();

extern  FILE*   _REL_stderr();

#define stdin   (_REL_stdin())

#define stdout  (_REL_stdout())

#define stderr  (_REL_stderr())

The first structure member, mode, indicates the I/O status and is internally defined as ACCSD_OUT/ADDSD_IN. The third member, unget_c, indicates the pushed-back character (stdin only) setting and is internally defined as -1.

When the definition is -1, it indicates that there is no pushed-back character. The second member, handle, indicates the I/O address. Set the value according to the debugger to be used.

[I/O address setting]

stdout->handle = 0xfffff000;

stderr->handle = 0x00fff000;

stdin->handle  = 0xfffff002;