vsprintf() - I/O Function

How is "vsprintf()" used in C++?

Explanation

vsprintf() is an I/O function is used to write the contents of the format string to the stream, with a pointer to a list of arguments replacing the argument list. This function returns the totalnumber of characters, but on failure a negative value is returned.

Syntax:

int vsprintf (char * str, const char * format, va_list arg );

The following table lists the type specifier used with vsprintf()

Type	Description
c	Character
d or i	Signed decimal integer
e	Scientific notation using e character
E	Scientific notation using E character
f	Decimal floating point
g	Use the shorter of %e or %f
G	Use the shorter of %E or %f
o	Signed octal
s	String of characters
u	Unsigned decimal integer
x	Unsigned hexadecimal integer
X	Unsigned hexadecimal integer(capital)
p	Pointer address
%	A % followed by another % character will write % to the stream.

Example :

#include <stdarg.h>
#include <stdio.h>
void vsform (char *string, char *format, ...);
char arr [] = "%s %s %s\n";
int main(void)
{
char string[100];
vsform(string, arr , "A", "B", "C");
printf("The strings are: %s\n", string);
}
void vsform(char *string, char *fmt, ...)
{
va_list arg_ptr;
va_start(arg_ptr, fmt);
vsprintf(string, fmt, arg_ptr);
va_end(arg_ptr);
}