Description

The C library function, The vsprintf() function ends formatted output to a string using an argument list passed to it.

Declaration

Following is the declaration for vsprintf() function.

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

Parameters

str - This is the pointer to an character array where the formatted string to be stored.

format - This is a null-terminated string containing the text to be written to stdout. It may contains some embedded format specifiers.

A format specifier follows this prototype:

%[flags][width][.precision][length]specifier

Where the specifier character at the end is the most significant component, since it defines the type and the interpretation of its corresponding argument:

The format specifier can also contain sub-specifiers: flags, width, .precision and modifiers (in that order), which are optional and follow these specifications:

arg - value representing a variable arguments list initialized with va_start. va_list is a special type defined in .

Return Value

The vsprintf function returns the number of characters stored in the array (not including the null character).

Example

#include <stdio.h>
#include <stdarg.h>
 
char buffer[128];
int writeFormatedString(char *format, ...)
{
   va_list args;
   int res;
 
   va_start(args, format);
   res = vsprintf(buffer, format, args);
   va_end(args);
 
   return(res);
}
 
int main()
{
   writeFormatedString("%d %f %s", 5, 5.5, "r4r.co.in");
   printf("%s\n", buffer);
    
   return(0);
}

Output

5 5.5 r4r.co.in