is this what you mean ?
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
void reverse (char local_arr[], int index, int len) {
int j;
for (j=len;j>0;j--) {
...
...
}
}
int main (int argc, char *argv[]) {
...
...
char arr[10][20];
...
memset(arr,'\0',20);
reverse(&arr[n][0],i,k);
...
return 0;
}