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i have problem with pointer..

so when i input:
2 3,
2 5,
2 7,
2 9,
2 11,
1 1
Output :
Nilai ; 3,
next = 4;

why testt.next is 4 ??
i want testt.next = 5;

What I have tried:

<pre><pre>#include <iostream>
 
using namespace std;
 
struct test
{
  int next;
  int previous;
  int nilai = 0;
};

int main()
{
	test *coba, testt;
	coba = &testt;
	int z;
	string perintah;
	int y = 0;
	while(true)
	{
		cout << "Input : ";
		cin >> perintah;
		if(perintah == "2")
		{
			if(testt.nilai != 0){
				*(++coba);
			}
			cin >> (*coba).nilai;
			y++;
		}
		if(perintah == "1")
		{
			cin >> z;
			for(int i = 0; i < y-z; i++)
			{
				*(--coba);
			}
			cout << "Nilai ; " << (*coba).nilai << endl;
			cout << "next / previous ? : ";
			cin >> perintah;
			if(perintah == "next")
			{
				*(++coba);
				testt.next = (*coba).nilai;
				cout << testt.next;
				for(int i = 1; i < y-z; i++)
				{
					*(++coba);
				}
			}
		}
	}
  return 0;
}
Posted 11-Jul-18 18:14pm
Updated 11-Jul-18 21:37pm
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Solution 1

Quote:
why testt.next is 4 ??
i want testt.next = 5;

How can we tell ? You forgot to tell what is supposed to do your code!

Your code do not behave the way you expect, and you don't understand why !

There is an almost universal solution: Run your code on debugger step by step, inspect variables.
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 know what your is supposed to do, it don't find bugs, it just help you to by showing you what is going on. When the code don't do what is expected, you are close to a bug.
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.

The downside of this solution:
- It is a DIY, you are the one tracking the problem and finding its roots, which lead to the solution.
The upside of this solution:
- It is also a great learning tool because it show you reality and you can see which expectation match reality.

secondary effects
- Your will be proud of finding bugs yourself.
- Your learning skills will improve.

You should find pretty quickly what is wrong.

Debugger - Wikipedia, the free encyclopedia[^]

Mastering Debugging in Visual Studio 2010 - A Beginner's Guide[^]
Basic Debugging with Visual Studio 2010 - YouTube[^]
1.11 — Debugging your program (stepping and breakpoints) | Learn C++[^]
The debugger is here to only show you what your code is doing and your task is to compare with what it should do.
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Solution 2

This statement
Quote:
*(++coba);
Probably doesn't do what you think it does: it is plainly equivalent to
++coba;

The compiler would have warned you if all the warnings were enabled.
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