C#•9mo ago

Why is my program showing my else statement when the response is valid?

Hello, I'm currently in a college course for C# and I'm learning loops right now. I'm doing an assignment where I'm keeping a running sum of a value and then stopping the program once the sum reaches the intended value. The program is supposed to look like the 2nd picture. My professor also attached pseudocode for use to use as a format (3nd picture). However, if I input a valid number twice, it doesn't give me the error message the first time but gives it on the second number even if they're the same number. What am I missing that could be causing this?

98 Replies

Angius•9mo ago

I'd use the debugger to see what the values are and when, and where the code goes at which point

MixOP•9mo ago

how can i see that in visual studio?

Pobiega•9mo ago

$debug

MODiX•9mo ago

https://docs.microsoft.com/en-us/visualstudio/get-started/csharp/tutorial-debugger?view=vs-2022

Tutorial: Debug C# code and inspect data - Visual Studio (Windows)

Learn features of the Visual Studio debugger and how to start the debugger, step through code, and inspect data in a C# application.

Angius•9mo ago

I do see the issue tho

Pobiega•9mo ago

the code could also be cleaned up to not have to do that whole temp reading twice

MixOP•9mo ago

i tried it without the temp reading line twice, but then i got results like this when i put in a number

Pobiega•9mo ago

well I didn't say you could just remove it 🙂

Angius•9mo ago

Protip: a do..while loop would be useful

Pobiega•9mo ago

MixOP•9mo ago

lol

Pobiega•9mo ago

while runs 0 or more times. do...while runs 1 or more times the difference is sometimes important, like here

MixOP•9mo ago

oh ok so i put the validTemp = line in the do {} part and then put the same while{} statement after it

Angius•9mo ago

string? input;
do
{
    Console.WriteLine("Yee!");
    input = Console.ReadLine();
} while (input.Equals("haw!", StringComparison.OrdinalIgnoreCase));

Console.WriteLine("Aww, you broke the chain...");

string? input;
do
{
    Console.WriteLine("Yee!");
    input = Console.ReadLine();
} while (input.Equals("haw!", StringComparison.OrdinalIgnoreCase));

Console.WriteLine("Aww, you broke the chain...");

MixOP•9mo ago

like this?

Pobiega•9mo ago

the while in a do..while doesnt have a body

Angius•9mo ago

Refer to my example

Pobiega•9mo ago

thats why you have a red squiggly there

Angius•9mo ago

MixOP•9mo ago

what do you mean by doesnt have a body?

Pobiega•9mo ago

while (true)
{
    //this is a body
}

do
{
    // this is a body
}
while(true);

while (true)
{
    //this is a body
}

do
{
    // this is a body
}
while(true);

MixOP•9mo ago

i see

Pobiega•9mo ago

the body moves to do in do..while

MixOP•9mo ago

so like this?

Pobiega•9mo ago

no you are still trying to have a body on the while Look at ZZZZZZZZs example. Look at mine. Read the error message your code has.

Angius•9mo ago

do {
    body
} while(condition); // <--- semicolon and nothing else

do {
    body
} while(condition); // <--- semicolon and nothing else

MixOP•9mo ago

so the error message i have says that there should be a ; where the red squiggly is

Angius•9mo ago

And the error message is correct

MixOP•9mo ago

but then my program looks like this when i add that. It's not including the "Enter temperature:" message when asking for new inputs

Pobiega•9mo ago

you cant do a single line fix my dude

Angius•9mo ago

Because your body is still outside of the do

Pobiega•9mo ago

you gotta actually fix your entire program

Angius•9mo ago

MixOP•9mo ago

ok so beyond the do...while loop, i have one other small error that i'm not sure what the cause is. i'm gettin this error message on the final line even though i have the line written above it in the exact same way with no errors

Angius•9mo ago

MixOP•9mo ago

you're a genius and i'm a moron lmao ty

Angius•9mo ago

I had a friend in college who I was helping because he was legally blind, he would often mistake {[( etc, so I'm sensitive to those errors lol

MixOP•9mo ago

yeah i've made plenty of those errors already as you can tell lol

Pobiega•9mo ago

did you manage to fix the loop?

MixOP•9mo ago

i think so, this is what i have

Angius•9mo ago

While. Has. No. Body. In. A. Do. While. Loop.

Pobiega•9mo ago

Look at where you are checking if its a valid temp and adding to your sum check WHERE that is being done, in regards to your loop

MixOP•9mo ago

so if the while has no body, i couldnt do an if...else loop inside of do...while loop? In my program, since I have to check if the temperature is valid, can i do that in the do...while loop or would that have to be outside of the loop? i'm really trying to wrap my head around this, sorry if it's aggravating lol

Pobiega•9mo ago

the do body has the loop in it

Angius•9mo ago

while (condition) {
    code
}

while (condition) {
    code
}

turns into

do
{
    code
} while (condition);

do
{
    code
} while (condition);

MixOP•9mo ago

because the picture i posted runs perfectly fine

Angius•9mo ago

It's that simple

Pobiega•9mo ago

it has to be inside the loop, as you are (potentially) reading multiple temperatures

MixOP•9mo ago

so in my case: do { Console.WriteLine("Enter Temperature:"); } while (temp != SENTINEL; and then my if statement under that all by itself?

MixOP•9mo ago

Pobiega•9mo ago

no no no no and no. no. no? no.

MixOP•9mo ago

:noted:

Pobiega•9mo ago

So, you know what a loop is right?

MixOP•9mo ago

i think so

Pobiega•9mo ago

and that only the stuff INSIDE the loop will be repeated?

MixOP•9mo ago

yes

Pobiega•9mo ago

with the code you just posted, how many times can count be incremented? assume happy flow

MixOP•9mo ago

+1 per input

Pobiega•9mo ago

wrong +1 total it can never ever be incremented twice why is that?

MixOP•9mo ago

because there's no way for the end of my if...else statement to point back to the beginning of the do statement? to restart

Pobiega•9mo ago

not entirely true, but I get what you mean so, how do we fix this? if we want the if(validtemp)... stuff to also be repeated

MixOP•9mo ago

i'm not sure i would say write the WriteLine and validTemp lines again but i dont think thats correct

Pobiega•9mo ago

hint: you have a loop. the if statement is currently not looping

MixOP•9mo ago

how is it not looping? i feel so dumb right now

Pobiega•9mo ago

because its outside the loop?

MixOP•9mo ago

but i thought the if...else was the loop

Pobiega•9mo ago

what the fuck?

MixOP•9mo ago

i would say you'd have to remove the ; but then i get an error

Pobiega•9mo ago

the red is the loop the yellow is outside the loop

MixOP•9mo ago

yeah so then in my head, i would remove the ; after the while part to include the if...else statement in the loop but then i get an error

Pobiega•9mo ago

refer back to https://discord.com/channels/143867839282020352/1213768151196766248/1213777445270982698

MODiX•9mo ago

Angius

while (condition) {
    code
}

while (condition) {
    code
}

turns into

do
{
    code
} while (condition);

do
{
    code
} while (condition);

Quoted by

<@105026391237480448> from #Why is my program showing my else statement when the response is valid? (click here)

React with ❌ to remove this embed.

Pobiega•9mo ago

if you want something looped, put it inside the do body if is not a looping construct

MixOP•9mo ago

ok so like this?

Pobiega•9mo ago

yep

MixOP•9mo ago

ok awesome

Pobiega•9mo ago

it can be cleaned up a bit, if you want

MixOP•9mo ago

how else could it be cleaned up? this is a beginner course, so it can't look too cleaned up if you know what i mean

Pobiega•9mo ago

😄 yeah I get it

MixOP•9mo ago

thank you so much for sticking with me through this btw, i really really appreciate it

Pobiega•9mo ago

validTemp = a..z;
if(validTemp)
{
  ...

validTemp = a..z;
if(validTemp)
{
  ...

is the same as

if(a..z)
{
  ...

if(a..z)
{
  ...

MixOP•9mo ago

ah ok i see, i just formatted it like that because thats my professor had it in the pseudocode she provided

MixOP•9mo ago

Pobiega•9mo ago

if you want extra style points, read up on pattern matching in conditions, and early exit as part of understanding your problem, I wrote my own solution to it and its quite a bit shorter

MixOP•9mo ago

can i see?

Pobiega•9mo ago

const int MIN_TEMP = -20;
const int MAX_TEMP = 120;
const int SENTINEL = 999;

int sum = 0;
int count = 0;

int temp;
do
{
    Console.WriteLine($"Enter temperature between {MIN_TEMP} and {MAX_TEMP}. Enter {SENTINEL} to stop.");
    if (!(int.TryParse(Console.ReadLine(), out temp) && temp is >= MIN_TEMP and <= MAX_TEMP))
    {
        Console.WriteLine($"Valid temperatures range between  {MIN_TEMP} and {MAX_TEMP}. Please try again.");
        continue;
    }

    sum += temp;
    count++;
} while (temp != SENTINEL);

var mean = sum / count;
Console.WriteLine($"You entered {count} temperatures.");
Console.WriteLine($"The mean temperature is {mean} degrees.");

const int MIN_TEMP = -20;
const int MAX_TEMP = 120;
const int SENTINEL = 999;

int sum = 0;
int count = 0;

int temp;
do
{
    Console.WriteLine($"Enter temperature between {MIN_TEMP} and {MAX_TEMP}. Enter {SENTINEL} to stop.");
    if (!(int.TryParse(Console.ReadLine(), out temp) && temp is >= MIN_TEMP and <= MAX_TEMP))
    {
        Console.WriteLine($"Valid temperatures range between  {MIN_TEMP} and {MAX_TEMP}. Please try again.");
        continue;
    }

    sum += temp;
    count++;
} while (temp != SENTINEL);

var mean = sum / count;
Console.WriteLine($"You entered {count} temperatures.");
Console.WriteLine($"The mean temperature is {mean} degrees.");

actually there might be an imbalanced parens in there no, we good 🙂

MixOP•9mo ago

ok so as far as the string interpolation in your code, i noticed you dont have any of the placeholders like I had in my code. Why is that?

Pobiega•9mo ago

because I'm using actual string interpolation, and you used string formatting see the dollar sign at the start of my strings?

MixOP•9mo ago

yeah

Pobiega•9mo ago

that indicates that string interpolation is active

MixOP•9mo ago

oh wait yeah you're right, i've done that before so i should probably rewrite my WriteLine like you did instead of the string formatting

Pobiega•9mo ago

imho, yes. other stuff to notice about my solution: temp is >= MIN_TEMP and <= MAX_TEMP if (!(int.TryParse... + continue; the first is pattern matching, and the second is "early exit" the idea is that instead of checking for valid, we check for INVALID because then we can stop right there

MixOP•9mo ago

i see

Pobiega•9mo ago

so if temp is not valid, print an error and restart the loop instead of go into an if-pyramid and stack elses at the end

MixOP•9mo ago

yeah that seems a lot cleaner well, its currently 5 am for me lol. thank you so much again for your help! i really appreciate it

Pobiega•9mo ago

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Why is my program showing my else statement when the response is valid?