Visual studio 2017 doesn't show errors, but there are build errors.

Question

0.00/5 (No votes)

See more:

Visual Studio 2017 isn't showing any errors in the code, and the error list is empty, but it says that there are build errors when I try to run my code. (it is a console application if that helps)

Visual Studio has been doing this for other console applications that i have been trying to make too.

VS is also showing other errors, just not whatever is causing the build errors.

Here is the code:

using System;
using System.Collections.Generic;

namespace ConsoleApp5
{
    class Program
    {
        static void Main()
        {
            int[] vals = {6, 5, 3, 1, 8, 7, 2, 4};
            //List<int> vals = new List<int> { 6, 5, 3, 1, 8, 7, 2, 4 };
            int n = 8;
            

            for (int i = 0; i < n; i++)//<= or <?
            {
                
                for (int j = 0; j < n - 1; j += 1 )
                {
                    if (vals[j] > vals[j + 1])
                    {
                        int x = vals[j];
                        int y = vals[j + 1];
                        vals[j] = y;
                        vals[j + 1] = x;
                        
                        //vals[j + 1] = vals[j];
                    }
                    
                }
            }

            foreach (int num in vals)
            {
                Console.WriteLine(vals[num]);
            }
            
            
            
            
        }
    }
}

What I have tried:

turning VS off and on again,
turning my computer on and off again,
powering my computer off and on again,
making a completely new console app,

none of these changed anything.

Posted 4-May-19 19:28pm

i like food

Updated 4-May-19 21:42pm

v2

Add a Solution

Comments

Richard MacCutchan 5-May-19 3:35am

What are the error messages?

2 solutions

Solution 2

It is your final loop that is the problem. You are using the actual value in the array as an index into the array:

C#

foreach (int num in vals)
{
    Console.WriteLine(vals[num]);
}

It should be:

C#

foreach (int num in vals)
{
    Console.WriteLine(num); // num is already the actual array item.
}

[edit]
Incidentally you need to learn the difference between compile, link and execution errors. What you had here was an execution error.
[/edit]

Posted 4-May-19 21:43pm

Richard MacCutchan

Updated 4-May-19 22:40pm

v2

Comments

BillWoodruff 5-May-19 9:28am

+5

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

OriginalGriff · Accepted Answer · 2019-05-04T19:55:00

Compiling does not mean your code is right! :laugh:
Think of the development process as writing an email: compiling successfully means that you wrote the email in the right language - English, rather than German for example - not that the email contained the message you wanted to send.

Not all error messages happen when you compile - some happen when you run your code, and it does something silly.

So now you enter the second stage of development (in reality it's the fourth or fifth, but you'll come to the earlier stages later): Testing and Debugging.

Start by looking at what it does do, and how that differs from what you wanted. This is important, because it give you information as to why it's doing it. For example, if a program is intended to let the user enter a number and it doubles it and prints the answer, then if the input / output was like this:

Input   Expected output    Actual output
  1            2                 1
  2            4                 4
  3            6                 9
  4            8                16

Then it's fairly obvious that the problem is with the bit which doubles it - it's not adding itself to itself, or multiplying it by 2, it's multiplying it by itself and returning the square of the input.
So with that, you can look at the code and it's obvious that it's somewhere here:

C#

private int Double(int value)
   {
   return value * value;
   }

Once you have an idea what might be going wrong, start using the debugger to find out why. Put a breakpoint on the first line of the method, and run your app. When it reaches the breakpoint, the debugger will stop, and hand control over to you. You can now run your code line-by-line (called "single stepping") and look at (or even change) variable contents as necessary (heck, you can even change the code and try again if you need to).
Think about what each line in the code should do before you execute it, and compare that to what it actually did when you use the "Step over" button to execute each line in turn. Did it do what you expect? If so, move on to the next line.
If not, why not? How does it differ?
Hopefully, that should help you locate which part of that code has a problem, and what the problem is.
This is a skill, and it's one which is well worth developing as it helps you in the real world as well as in development. And like all skills, it only improves by use!

I'll even give you a clue: what does foreach do? What value doe it put in num as it goes round the loop? If you aren't sure, use the debugger to check and yoru problem should become obvious.