vfprintf, vfwprintf
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Header File
stdio.h
Category
Input/output Routines
Prototype
int vfprintf(FILE *stream, const char *format, va_list arglist);
int vfwprintf(FILE *stream, const wchar_t *format, va_list arglist);
Description
Writes formatted output to a stream.
The v...printf functions are known as alternate entry points for the ...printf functions. They behave exactly like their ...printf counterparts, but they accept a pointer to a list of arguments instead of an argument list.
For details on format specifiers, see printf Format Specifiers.
vfprintf accepts a pointer to a series of arguments, applies to each argument a format specifier contained in the format string pointed to by format, and outputs the formatted data to a stream. There must be the same number of format specifiers as arguments.
Return Value
On success, vfprintf returns the number of bytes output.
On error, it returns EOF.
Example
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
FILE *fp;
int vfpf(char *fmt, ...)
{
va_list argptr;
int cnt;
va_start(argptr, fmt);
cnt = vfprintf(fp, fmt, argptr);
va_end(argptr);
return(cnt);
}
int main(void)
{
int inumber = 30;
float fnumber = 90.0;
char string[4] = "abc";
fp = tmpfile();
if (fp == NULL)
{
perror("tmpfile() call");
exit(1);
}
vfpf("%d %f %s", inumber, fnumber, string);
rewind(fp);
fscanf(fp,"%d %f %s", &inumber, &fnumber, string);
printf("%d %f %s\n", inumber, fnumber, string);
fclose(fp);
return 0;
}
Portability
| POSIX | Win32 | ANSI C | ANSI C++ | |
|---|---|---|---|---|
|
vfprintf |
+ |
+ |
+ |
+ |
|
vfwprintf |
+ |
+ |
+ |