#include
#include
#include
using namespace std;
int main(int argc, char *argv[])
{
if(argc!=3) {
cout << "Usage: Reverse \n";
return 1;
}
fstream inout(argv[1], ios::in | ios::out | ios::binary);
if(!inout) {
cout << "Cannot open input file.\n";
return 1;
}
long e, i, j;
char c1, c2;
e = atol(argv[2]);
for(i = 0, j = e; i < j; i++, j--) {
inout.seekg(i, ios::beg);
inout.get(c1);
inout.seekg(j, ios::beg);
inout.get(c2);
inout.seekp(i, ios::beg);
inout.put(c2);
inout.seekp(j, ios::beg);
inout.put(c1);
}
inout.close();
return 0;
}