Arrange strings

/*exercise 3.3:Arrange strings*/

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

void expand(char s1[],char s2[] )
{
    int gap,i,j,n,temp;
    n=strlen(s1);
    i=0;
    for(i=0;i<=n;i++)
    {
      s2[i] = s1[i];

    }
    for (gap = n/2;gap > 0;gap /=2)
      for(i=gap;i<n;i++)
        for(j=i-gap;j>=0 && s2[j] > s2[j+gap];j-=gap) {
        temp = s2[j];
        s2[j] = s2[j+gap];
        s2[j+gap]=temp;
        }

}

int main()
{
    char s1[1000] ="afwahefjsdhfahejfhdsnajsdnjsnafhj";
    char s2[1000];
    expand(s1,s2);
    printf("orginal string:%s\n",s1);
    printf("odered string:%s\n",s2);
    return 0;
}