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snprintf - identical to sprintf() except that a maximum of num-1 characters will be stored in C

//Header file:     #include <stdio.h>  
//Declaration:     int snprintf(char * restrict buf, size_t num, const char * restrict format, ...) 

#include <stdio.h>

int main ()
  char buffer [50];
  int n, a=5, b=3;
  n=snprintf (buffer, 5,"%d plus %d is %d", a, b, a+b);
  printf ("[%s] is a %d char long string\n",buffer,n);
  return 0;