#include <stdio.h>

int sprintf (
  char *buffer,            /* storage buffer */
  const char *fmtstr       /* format string */
  <[>, arguments ...<]>);    /* additional arguments */

The sprintf function formats a series of strings and numeric values and stores the resulting string in buffer. This function is similar to the printf routine, but it stores the formatted output in buffer rather than sending it to the output stream.

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 list of arguments are converted and output according to the corresponding format specifications in fmtstr.

The sprintf function returns the number of characters actually written to buffer.

gets, puts, vprintf, vsprintf

#include <stdio.h>

void tst_sprintf (void) {
  char buf [100];
  int n;
  int a,b;
  float pi;

  a = 123;
  b = 456;
  pi = 3.14159;

  n = sprintf (buf, "%f\n", 1.1);
  n += sprintf (buf+n, "%d\n", a);
  n += sprintf (buf+n, "%d %s %g", b, "---", pi);

  puts (buf);
}