vfscanf_s, vfwscanf_s
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Header File
stdio.h
Category
Formatted input/output functions
Prototype
int vfscanf_s(FILE * restrict stream, const char * restrict format, va_list arg);
int vfwscanf_s(FILE * restrict stream, const wchar_t * restrict format, va_list arg);
Description
Replaces vfscanf adding security enhancements.
The v...scanf functions are known as alternate entry points for the ...scanf functions. They behave exactly like their ...scanf counterparts but they accept a pointer to a list of arguments instead of an argument list.
vfscanf_s is equivalent to vfscanf, but it adds run-time constraints regarding the validity of stream, format, and the items in arg corresponding to a %s format specifier (all mentioned earlier must not be null pointers.)
Return Value
vfscanf_s returns the number of input fields successfully scanned, converted, and stored; the return value does not include scanned fields that were not stored. If no fields were stored, the return value is 0.
If vfscanf_s encounters an input error, the return value is EOF.
Example
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
FILE *fp;
int vfsf(char *fmt, ...)
{
va_list argptr;
int cnt;
va_start(argptr, fmt);
cnt = vfscanf_s(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);
}
fprintf(fp,"%d %f %s\n",inumber,fnumber,string);
rewind(fp);
vfsf("%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++ |
|---|---|---|---|
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