c++ vector reverse algorithm

Question

I am trying to make a simple program which basically reverse the sequence of the vector. In other words after the program is ran, `x[0]` should be equal to `5`. The output which I am currently getting is `5234`. The `1` goes missing somewhere. I did include the `` header. Thanks in advance. ``` int main() { vector x(5); x[0] = 1; x[1] = 2; x[2] = 3; x[3] = 4; x[4] = 5; for(int z = 0; z < x.size()-1; z++) { int temp = x[x.size() - (1+z)]; x[x.size() - (1+z)] = x[z]; x[z] = temp; } for(int s = 0; s < x.size() - 1; s++) { cout << x[s] << endl; } return 0; } ```

Accepted Answer

Take a step back a minute. What do you think this will do if I just put in swap (pseudo code)

```
for( elt1 = begin, elt2 = end-1; elt1 != end; ++elt1, --elt2 )
{
    iter_swap( elt1, elt2 );
}
```

This will not reverse your collection. Or rather it will, but will then reverse it back again leaving you where you started. Say your collection has 4 elements:

```
swap( 0, 3 )
swap( 1, 2 )
swap( 2, 1 )
swap( 3, 0 )
```

So your terminating condition is wrong, you should only swap halfway...

c++ vector reverse algorithm

Solution

Problem