Vector does not change elements

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I have to add a new element and move some others in my vector in this program \/, but vector elements do not want to change at all.

C++

#include <iostream>
#include <deque>

using namespace std;

int main()
{
	int n;
	cin >> n;
    vector <int> v;
    for (auto i = 0, j = 0; i < n; i++)
    {
    	cin>>j;
        v.push_back(j);
    }
    //
    int max = 0, ind = 0;
    for (auto i:v)
    	if (max <= i)
        {     	
        	max = i;
        	ind = i;
        }
    //
    v.push_back(0);
    for (auto i = n, j =0; i > ind+1; i--)
    {    	j = v[i]; -----this code does not work
          v[i] = v[i-1];-------this code does not work
          v[i-1] = j;----------this code does not work
    }
    v[ind+1] = v[ind];--------- this code does not work
    //
   for (auto i:v)
    	      cout << i << ' ';
  	cout << endl;
	return 0;
}

I know it may seem hilarious, but it does!
Example of input:
3
3 1 1
Expected output:
3 3 1 1
Real output:
3 1 1 0

What I have tried:

read several articles about vector type on the Net;
tried to use swap() function, but it does not work either;
tried to use deque or queue instead of vector - same result;
i think that that code must work and do not know why it doesn`t.

Posted 17-Nov-17 7:16am

Member 13527256

Updated 17-Nov-17 16:29pm

Patrice T

v4

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Comments

Richard MacCutchan 17-Nov-17 13:43pm

Step through the code with the debugger and see why.

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Patrice T · Accepted Answer · 2017-11-17T16:29:00

Quote:
i think that that code must work and do not know why it doesn`t.

Launch the debugger, on every step, check that everything is what it should.

C++

for (auto i = n, j =0; i > ind+1; i--)

Are you using the maximum value in vector as the ending position in loop ?
Unless this is carefully planed, you are in for great troubles.

There is a tool that allow you to see what your code is doing, its name is debugger. It is also a great learning tool because it show you reality and you can see which expectation match reality.
When you don't understand what your code is doing or why it does what it does, the answer is debugger.
Use the debugger to see what your code is doing. Just set a breakpoint and see your code performing, the debugger allow you to execute lines 1 by 1 and to inspect variables as it execute.

Debugger - Wikipedia, the free encyclopedia[^]

Mastering Debugging in Visual Studio 2010 - A Beginner's Guide[^]
Basic Debugging with Visual Studio 2010 - YouTube[^]
The debugger is here to show you what your code is doing and your task is to compare with what it should do.
There is no magic in the debugger, it don't find bugs, it just help you to. When the code don't do what is expected, you are close to a bug.