I want to read an string/array from the terminal/keyboard and write it to an string variable.

That’s easy:
— snip —

printf("Please enter the string now ... n") ;
scanf("%s", str1)

— snip —

But I also want to be sure that the string/array is not bigger than a certain size. But my approach doesn’t work at al and the user can produce a buffer overflow.

— snip —
#include<stdio.h> #include<stdlib.h> #include<string.h>

#define MAX_STRG 10


int main ( int argc, char *argv[] ) {

   char str1[MAX_STRG/2]="One", str2[MAX_STRG/2]="Two" ;
   int pos = 0, check = 1 ;
   size_t lenstr = 0 ;

  /* get the string   */
   while(check==1){
      printf("Please enter the first string now ... n") ;
      scanf("%5s", str1) ;

      printf("Please enter the second string now ... n") ;
      scanf("%5s", str2) ;

 /* string size in bytes*/
      lenstr = sizeof(str1) + sizeof(str2) ;

      printf("n string1 string2 position StrgLenn %st %st %dt %d nn", str1, 

str2, pos, (int)lenstr) ;

      if (lenstr<=MAX_STRG+1){
         check = 0 ;
       }
   }`

— snip —

But my check is to late and the string will be already written to memory when I check. I thought giving the size with the scanf statement would do the check but no.

In general I would like to find a way how to enter a string within defined length boundaries and if the string is to large an error is produced

Thanks in advance
sake