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Cx51 User's Guide

Cx51 Introduction Compiling Programs Language Extensions Preprocessor Advanced Programming 8051 Derivatives Error Messages Library Reference Library Files Source Code Standard Types jmp_buf size_t va_list wchar_t Macros CBYTE CWORD DBYTE DWORD FARRAY FCARRAY FCVAR FVAR PBYTE PWORD XBYTE XWORD Routines By Category Buffer Manipulation Routines Character Routines Data Conversion Routines Intrinsic Routines Math Routines Memory Allocation Routines Stream I/O Routines String Routines Variable Length Argument Routines Miscellaneous Routines Include Files SFR Definitions 80c517.h absacc.h assert.h ctype.h float.h intrins.h limits.h math.h rtx51tny.h setjmp.h stdarg.h stddef.h stdio.h stdlib.h string.h Reference _chkfloat_ _crol_ _cror_ _getkey _irol_ _iror_ _lrol_ _lror_ _nop_ _pop_ _push_ _testbit_ _tolower _toupper abs acos acos517 asin asin517 assert atan atan2 atan517 atof atof517 atoi atol cabs calloc ceil cos cos517 cosh exp exp517 fabs floor fmod free getchar gets init_mempool isalnum isalpha iscntrl isdigit isgraph islower isprint ispunct isspace isupper isxdigit labs log log10 log10517 log517 longjmp malloc memccpy memchr memcmp memcpy memmove memset modf offsetof pow printf printf517 putchar puts rand realloc scanf scanf517 setjmp sin sin517 sinh sprintf sprintf517 sqrt sqrt517 srand sscanf sscanf517 strcat strchr strcmp strcpy strcspn strlen strncat strncmp strncpy strpbrk strpos strrchr strrpbrk strrpos strspn strstr strtod strtod517 strtok strtol strtoul switchbank tan tan517 tanh toascii toint tolower toupper ungetchar va_arg va_end va_start vprintf vsprintf Appendix

vprintf

Summary
#include <stdio.h>

void vprintf (
  const char *fmtstr,   /* pointer to format string */
  char *argptr);        /* pointer to argument list */
Description

The vprintf function formats a series of strings and numeric values and builds a string to write to the output stream using the putchar function. This function is similar to the printf routine, but it accepts a pointer to a list of arguments instead of an argument list.

The fmtstr argument is a pointer to a format string which has the same form and function as the printf function's format string. The argptr argument points to a list of arguments that are converted and output according to the corresponding format specifications in fmtstr.

Note

  • This function is implementation-specific and is based on the operation of the putchar function. This function, as provided in the standard library, writes characters using the microcontroller's serial port. Custom functions may use other I/O devices.
Return Value

The vprintf function returns the number of characters actually written to the output stream.

See Also

gets, puts, sprintf, sscanf, vsprintf

Example
#include <stdio.h>
#include <stdarg.h>

void error (char *fmt, ...) {
  va_list arg_ptr;
  va_start (arg_ptr, fmt); /* format string */
  vprintf (fmt, arg_ptr);
  va_end (arg_ptr);
}

void tst_vprintf (void) {
  int i;

  i = 1000;

  /* call error with one parameter */
  error ("Error: '%d' number too large\n", i);

  /* call error with just a format string */
  error ("Syntax Error\n");
}
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