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C#•2mo ago

Understanding get; set; backing field requirements.

Per the instructions (full instructions listed in the comments) "make a ToString() method that returns a string containing all job information in the following format." Job 111 Smith exterior paint 20 hours @$45.00 per hour. Total price is $900.00

my ToString Method so far 
            public override string ToString()
            {
                Console.WriteLine($"Job {jobNumber} {customer} exterior paint {hours} hours @{price} per hour. Total price is {totalPrice}");
            }

my ToString Method so far 
            public override string ToString()
            {
                Console.WriteLine($"Job {jobNumber} {customer} exterior paint {hours} hours @{price} per hour. Total price is {totalPrice}");
            }

The very last {} totalPrice needs to be created. Which requires defining it in a get set

            private const double hourlyrate = 45.00;
            private double hours;
            private double totalPrice; 
            private double totalPrice
            {
                get; set
                {
                    hours = value;
                    price = hourlyrate * price;
                }
            }

            private const double hourlyrate = 45.00;
            private double hours;
            private double totalPrice; 
            private double totalPrice
            {
                get; set
                {
                    hours = value;
                    price = hourlyrate * price;
                }
            }

I was under the impression that if you are going to write a custom get set that is NOT an auto property, you must create a backing field for it. So I made a totalPrice double and tried to run the code. I got this error. why is this?

/workspaces/9780357429235_farrell-c-sharp-aaba885a-f662-4800-a980-c6b80f6b520c/chapter10/ex03A/student/JobDemo.cs(57,41): error CS0501: 'JobDemo.Job.totalPrice.get' must declare a body because it is not marked abstract, extern, or partial [/workspaces/9780357429235_farrell-c-sharp-aaba885a-f662-4800-a980-c6b80f6b520c/chapter10/ex03A/student/JobDemo.csproj]

/workspaces/9780357429235_farrell-c-sharp-aaba885a-f662-4800-a980-c6b80f6b520c/chapter10/ex03A/student/JobDemo.cs(57,41): error CS0501: 'JobDemo.Job.totalPrice.get' must declare a body because it is not marked abstract, extern, or partial [/workspaces/9780357429235_farrell-c-sharp-aaba885a-f662-4800-a980-c6b80f6b520c/chapter10/ex03A/student/JobDemo.csproj]

55 Replies

strikeouts27OP•2mo ago

I am thinking that my problem is I named the backing field the same as my Property attempting a casing change

ero•2mo ago

is there a particular reason why you think you need a property instead of just a local inside ToString?

strikeouts27OP•2mo ago

well I attempted to do hours * price but it gave me pushback

jcotton42•2mo ago

what pushback?

strikeouts27OP•2mo ago

checking notes....

jcotton42•2mo ago

Also, your backing field needs a different name from your prop. As for the error, since you provided a set impl, you're no longer in autoprop land, so the compiler doesn't konw the backing field, so it can't fill in get for you.

strikeouts27OP•2mo ago

so even if I succeeded in making a property with a backing field I will still fail.

jcotton42•2mo ago

private double totalPrice;
public double TotalPrice
{
  get { return totalPrice; }
  set { totalPrice = value; }
}

private double totalPrice;
public double TotalPrice
{
  get { return totalPrice; }
  set { totalPrice = value; }
}

or whatever but also, i don't see why you can't just use an autoprop here just compute the total price inside ToString err, sorry, I don't see why you need a TotalPrice prop at all

strikeouts27OP•2mo ago

the purpose of the ToString function is to get the total job cost currently there is price at 45.00 in a variable. and hours in a variable.

jcotton42•2mo ago

@strikeouts27 "the function" being what? ToString? yeah, so compute it in there

strikeouts27OP•2mo ago

attempting...

mtreit•2mo ago

The assignment says:

the price field value is calculated as estimated hours times $45.00 ($45.00 / hour) whenever the hours value is set.

strikeouts27OP•2mo ago

I think i tried simply doing price * hours and it wasn't reachable for the tostring method.

cs 
private const double hourlyrate = 45.00;
            private double hours;
            private double totalPrice; 
            public double TotalPrice
            {
                get
                {
                    return totalPrice;
                }
                set {
                        { totalPrice = value; }
                    }
            }

cs 
private const double hourlyrate = 45.00;
            private double hours;
            private double totalPrice; 
            public double TotalPrice
            {
                get
                {
                    return totalPrice;
                }
                set {
                        { totalPrice = value; }
                    }
            }

error method must have a return type, checking tostring now

Angius•2mo ago

There's no method in this code

jcotton42•2mo ago

that error isn't about your prop yeah, that

Angius•2mo ago

(also, $code to make it more readable)

MODiX•2mo ago

To post C# code type the following: ```cs // code here ``` Get an example by typing $codegif in chat For longer snippets, use: https://paste.mod.gg/

strikeouts27OP•2mo ago

https://paste.mod.gg/eleywrdlbxex/0 error code

cs 
/workspaces/9780357429235_farrell-c-sharp-aaba885a-f662-4800-a980-c6b80f6b520c/chapter10/ex03A/student/JobDemo.cs(105,95): error CS0103: The name 'price' does not exist in the current context [/workspaces/9780357429235_farrell-c-sharp-aaba885a-f662-4800-a980-c6b80f6b520c/chapter10/ex03A/student/JobDemo.csproj]
/workspaces/9780357429235_farrell-c-sharp-aaba885a-f662-4800-a980-c6b80f6b520c/chapter10/ex03A/student/JobDemo.cs(103,36): error CS0161: 'JobDemo.Job.ToString()': not all code paths return a value [/workspaces/9780357429235_farrell-c-sharp-aaba885a-f662-4800-a980-c6b80f6b520c/chapter10/ex03A/student/JobDemo.csproj]

cs 
/workspaces/9780357429235_farrell-c-sharp-aaba885a-f662-4800-a980-c6b80f6b520c/chapter10/ex03A/student/JobDemo.cs(105,95): error CS0103: The name 'price' does not exist in the current context [/workspaces/9780357429235_farrell-c-sharp-aaba885a-f662-4800-a980-c6b80f6b520c/chapter10/ex03A/student/JobDemo.csproj]
/workspaces/9780357429235_farrell-c-sharp-aaba885a-f662-4800-a980-c6b80f6b520c/chapter10/ex03A/student/JobDemo.cs(103,36): error CS0161: 'JobDemo.Job.ToString()': not all code paths return a value [/workspaces/9780357429235_farrell-c-sharp-aaba885a-f662-4800-a980-c6b80f6b520c/chapter10/ex03A/student/JobDemo.csproj]

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strikeouts27OP•2mo ago

I'm on a new error now I consider this progress.

Angius•2mo ago

Well, the error is quite obvious

strikeouts27OP•2mo ago

price is not defined so I need to make it accessible for the method to be used. It is passed in as a parameter. Considering this.

Angius•2mo ago

There's no field named price, no property named price, no other member named price, no parameter named price nor a local variable named price Is it? ToString(), where you use price, has no parameters at all

strikeouts27OP•2mo ago

oh thats right I destroyed it making the backing field so just change the price to hourly rate

Angius•2mo ago

For example, yes

strikeouts27OP•2mo ago

okay cool that error dissapeared. attempting to get it to print out output. trying to solve on my own. will come back if i have more questions.

Angius•2mo ago

:Ok:

strikeouts27OP•2mo ago

Okay I rediscovered the error that was preventing a calculation. Basically the complier is saying the job instance methods have not been created at the time of calculation. error code

/workspaces/9780357429235_farrell-c-sharp-aaba885a-f662-4800-a980-c6b80f6b520c/chapter10/ex03A/student/JobDemo.cs(59,41): error CS0236: A field initializer cannot reference the non-static field, method, or property 'JobDemo.Job.hours' [/workspaces/9780357429235_farrell-c-sharp-aaba885a-f662-4800-a980-c6b80f6b520c/chapter10/ex03A/student/JobDemo.csproj]

/workspaces/9780357429235_farrell-c-sharp-aaba885a-f662-4800-a980-c6b80f6b520c/chapter10/ex03A/student/JobDemo.cs(59,41): error CS0236: A field initializer cannot reference the non-static field, method, or property 'JobDemo.Job.hours' [/workspaces/9780357429235_farrell-c-sharp-aaba885a-f662-4800-a980-c6b80f6b520c/chapter10/ex03A/student/JobDemo.csproj]

https://paste.mod.gg/wtfaufnfbwjw/0

            public override string ToString()
            {
                return $"Job {jobNumber} {customer} {description} {hours} hours @{hourlyrate} per hour. Total price is {TotalPrice}.";
            }

            public override string ToString()
            {
                return $"Job {jobNumber} {customer} {description} {hours} hours @{hourlyrate} per hour. Total price is {TotalPrice}.";
            }

        public class Job
        {
            private const double hourlyrate = 45.00;
            private double hours;
            private double totalPrice = hours * hourlyrate; 
            public double TotalPrice
            {
                get
                {
                    return totalPrice;
                }
                set {
                        { totalPrice = value; }
                    }
            }

        public class Job
        {
            private const double hourlyrate = 45.00;
            private double hours;
            private double totalPrice = hours * hourlyrate; 
            public double TotalPrice
            {
                get
                {
                    return totalPrice;
                }
                set {
                        { totalPrice = value; }
                    }
            }

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mtreit•2mo ago

The error is telling you exactly what the issue is.

mtreit•2mo ago

You can't do this:

mtreit•2mo ago

The initializer for totalPrices (that is, the stuff on the right-side of the equal sign) cannot refer to other non-static fields. In this case, hours

strikeouts27OP•2mo ago

im thinking...

mtreit•2mo ago

At the time that initializer runs, hours does not yet have a value.

strikeouts27OP•2mo ago

if its a timing issue than maybe i make a method? I would need to make something that runs after the values are inintalized correct? And methods calls run after instantiation.

Angius•2mo ago

Or while they are being initialized (*cough cough* constructor)

strikeouts27OP•2mo ago

ah, so your saying that its possible to quick start a method call by editing the constructor with a called method. so on creation it runs the method.

Angius•2mo ago

Assuming you even need a method here But sure

strikeouts27OP•2mo ago

I'm adding this to my textbook notes and this error message. okay I will look up how to do that.

strikeouts27OP•2mo ago

            public Job(int jobNumber, string customer, string description, double hours) : this(hours, hourlyrate, TotalPrice)
            {
                this.jobNumber = jobNumber;
                this.customer = customer;
                this.description = description;
                this.hours = hours;
            }

            public Job(int jobNumber, string customer, string description, double hours) : this(hours, hourlyrate, TotalPrice)
            {
                this.jobNumber = jobNumber;
                this.customer = customer;
                this.description = description;
                this.hours = hours;
            }

https://paste.mod.gg/unwltqceovem/0

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strikeouts27OP•2mo ago

error message

/workspaces/9780357429235_farrell-c-sharp-aaba885a-f662-4800-a980-c6b80f6b520c/chapter10/ex03A/student/JobDemo.cs(59,41): error CS0236: A field initializer cannot reference the non-static field, method, or property 'JobDemo.Job.hours' [/workspaces/9780357429235_farrell-c-sharp-aaba885a-f662-4800-a980-c6b80f6b520c/chapter10/ex03A/student/JobDemo.csproj]

/workspaces/9780357429235_farrell-c-sharp-aaba885a-f662-4800-a980-c6b80f6b520c/chapter10/ex03A/student/JobDemo.cs(59,41): error CS0236: A field initializer cannot reference the non-static field, method, or property 'JobDemo.Job.hours' [/workspaces/9780357429235_farrell-c-sharp-aaba885a-f662-4800-a980-c6b80f6b520c/chapter10/ex03A/student/JobDemo.csproj]

My question is, why is it not instantiating hours, hourlyrate, and TotalPrice?

MODiX•2mo ago

mtreit

You can't do this:

Quoted by

<@406536255426396160> from #Understanding get; set; backing field requirements. (click here)

React with ❌ to remove this embed.

MODiX•2mo ago

mtreit

At the time that initializer runs, hours does not yet have a value.

Quoted by

<@406536255426396160> from #Understanding get; set; backing field requirements. (click here)

React with ❌ to remove this embed.

strikeouts27OP•2mo ago

didnt my constructor intializer take care of that?

mtreit•2mo ago

private double totalPrice = hours * hourlyrate;  // The constructor runs after this.

private double totalPrice = hours * hourlyrate;  // The constructor runs after this.

strikeouts27OP•2mo ago

so making a constructor means its too late.

mtreit•2mo ago

You can never do what you are trying because the constructor doesn't run until all of the field intializers have executed. It means you should stop trying to do any math in the field initializer. And do it in the constructor instead.

strikeouts27OP•2mo ago

            public Job(int jobNumber, string customer, string description, double hours, double hourlyRate)
            {
                jobNumber = jobNumber;
                this.customer = customer;
                description = description;
                this.hours = hours;

                totalPrice = hours * hourlyrate; 
            }

            public Job(int jobNumber, string customer, string description, double hours, double hourlyRate)
            {
                jobNumber = jobNumber;
                this.customer = customer;
                description = description;
                this.hours = hours;

                totalPrice = hours * hourlyrate; 
            }

mtreit•2mo ago

You might fix up your use of this to be consistent.

strikeouts27OP•2mo ago

so the field zone is a no math zone. okay i will edit my notes to that.

mtreit•2mo ago

Well, no, you can do math with constant or static values. Just not using values from other instance members, like other fields.

strikeouts27OP•2mo ago

PROJECT COMPLETE! So that next time i can be a better researcher does anyone have any reccomended learning materials for looking up C# related problems? Learning websites?

mtreit•2mo ago

We normally suggest people start with $helloworld

MODiX•2mo ago

Get started with beginner tutorials - Interactive text tutorial - Video tutorial - Fundamentals documentation

strikeouts27OP•2mo ago

So be it. Determined face.

mtreit•2mo ago

You can also do things like solve small programming problems using C# to get more experience with it. Advent of Code is great for this: https://adventofcode.com/ You can go back and do all of past years problems. For instance, go solve day 1 from every year for practice. Then do day 2. (They get harder in general as the days go on.) There is also $projects

MODiX•2mo ago

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