Error message in removing duplicate strings

[Tripswitch]

Hi,

My program removes the duplicate string(s) and outputs the unique strings but as soon as it does I get an error message saying stack around the variable buffer was corrupted?

#include<stdio.h>
#include <string.h>


int main(void) 
{
      char buffer[4][4]={"cat","mat","cat","hat"};
      int i, j, k;
      int a=4;
 
      for (i = 0;i < a; i++) 
      {
           for (j = i + 1; j < 4;) 
           {
                if (strcmp(buffer[j],buffer[i])==0)
                {
                     for (k = j; k < a; k++) 
                     {
                     strcpy(buffer[k],buffer[k+1]);
                     }

               a--;
               } 

         else
         j++;
         }
     }
 
   for (i = 0; i < a; i++) 
   {
      printf("%s", buffer[i]);
   }
 
   return (0);
}

[stahta01]

When k = 3; then k+1 is 4 which will be undefined access.

strcpy(buffer[k],buffer[k+1]);

Tim S.

[zub]

I advise you to use an assignment of NULL as an indication that the string is removed.

I advise you to check previous strings for uniqness, not next.

I advise you to create array of pointers, not two-dimensional array of chars.

I advise you to use puts instead of printf (in such simple cases, of course).

const char* buffer[4] = {
   "cat",
   "mat",
   "cat",
   "hat"
};

// skipped

for( i = 0; i < 4; ++i ) {
    if( buffer[i] ) { puts(buffer[i]); }
}