Need help with switch statements | Together C & C++ | Page 1

lethal crow Sep 17, 2022, 11:05 PM

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Hi, I'm trying to practice with switch statements and need help. It's not working.

#include <iostream>
#include <iomanip>
#include <cctype>
using namespace std;

float score1, score2, score3, score4, score5, scoreAverage, extraCredit;

cout << "Enter score 1 : ";
cin >> score1;
while (score1 < 0)
{
    cout << "Please enter a valid score : ";
    cin >> score1;
}
cout << "Enter score 2 : ";
cin >> score2;
while (score2 < 0)
{
    cout << "Please enter a valid score : ";
    cin >> score2;
}
cout << "Enter score 3 : ";
cin >> score3;
while (score3 < 0)
{
    cout << "Please enter a valid score : ";
    cin >> score3;
}
cout << "Enter score 4 : ";
cin >> score4;
while (score4 < 0)
{
    cout << "Please enter a valid score : ";
    cin >> score4;
}
cout << "Enter score 5 : ";
cin >> score5;
while (score5 < 0)
{
    cout << "Please enter a valid score : ";
    cin >> score5;
}
cout << "If you got any extra credit points enter them. If not enter 0 : ";
cin >> extraCredit;
scoreAverage = score1 + score2 + score3 + score4 + score5;
scoreAverage += extraCredit;
scoreAverage = scoreAverage / 5;
cout << scoreAverage;
switch(scoreAverage)
{
    case scoreAverage > 100 : cout << "You did an amazing job!" << endl;
    case scoreAverage >= 90 && scoreAverage <= 100 : cout << "You got an A. Nice job!" << endl;
    case scoreAverage >= 80 && scoreAverage < 90 : cout << "You got a B. Good job!" << endl;
    case scoreAverage >= 70 && scoreAverage < 80 : cout << "You got a C. Decent job. Try studying more." << endl;
    case scoreAverage >= 60 && scoreAverage < 70 : cout << "You got a D. Try studying more." << endl;
    case scoreAverage < 60 : cout << "You got a F. If you need help, please let me know what's wrong." << endl;
}

signal orchidBOT Sep 17, 2022, 11:05 PM

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prime vale Sep 17, 2022, 11:14 PM

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case statements can't contain conditions

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only literal values

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i.e. case 100:

lethal crow Sep 17, 2022, 11:16 PM

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prime vale case statements can't contain conditions

How would I use it for this code?

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Do I have to do case 100 case 99 case 98…..? Sounds like that would take a while

prime vale Sep 17, 2022, 11:17 PM

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you can't

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if you need conditions like that, you need an if

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I mean, sure, you can write out all possible cases but...

lethal crow Sep 17, 2022, 11:17 PM

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Oh god

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Yeah for this assignment we did this score program with if statements

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Which I already did

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But he said to do it again but with switch statements instead of if statements

prime vale Sep 17, 2022, 11:18 PM

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"Please enter a valid score"

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is there a maximum value you can assume?

lethal crow Sep 17, 2022, 11:19 PM

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There isn’t really a maximum

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He said just to make sure there are no values that are less than 0

prime vale Sep 17, 2022, 11:20 PM

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also your scores are floats

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cases can only be used for integers

lethal crow Sep 17, 2022, 11:20 PM

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Oh

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Ok I just changed that

prime vale Sep 17, 2022, 11:21 PM

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if you divided the score by 10, then there would be fewer cases you need to write

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except for all the > 100 (or > 10) numbers 😛

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an int can usually hold numbers of up to around 2 billion

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you could use default to catch those cases, though

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if you handle 0-9

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for example, say the score is 85
if you divide by 10 (if score is an integer), you get 8

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so case 8: will cover all scores from 80 to 89

lethal crow Sep 17, 2022, 11:26 PM

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ok i see

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i think i'll try to it like that

lethal crow Sep 17, 2022, 11:45 PM

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@prime vale I tried to do what you said but i'm having bit of an issue

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cout << "Enter score 1 : ";
cin >> score1;
while (score1 < 0)
{
    cout << "Please enter a valid score : ";
    cin >> score1;
}
cout << "Enter score 2 : ";
cin >> score2;
while (score2 < 0)
{
    cout << "Please enter a valid score : ";
    cin >> score2;
}
cout << "Enter score 3 : ";
cin >> score3;
while (score3 < 0)
{
    cout << "Please enter a valid score : ";
    cin >> score3;
}
cout << "Enter score 4 : ";
cin >> score4;
while (score4 < 0)
{
    cout << "Please enter a valid score : ";
    cin >> score4;
}
cout << "Enter score 5 : ";
cin >> score5;
while (score5 < 0)
{
    cout << "Please enter a valid score : ";
    cin >> score5;
}
cout << "If you got any extra credit points enter them. If not enter 0 : ";
cin >> extraCredit;
scoreAverage = score1 + score2 + score3 + score4 + score5;
scoreAverage += extraCredit;
scoreAverage = scoreAverage / 5;
cout << scoreAverage << endl;
scoreAverage = scoreAverage / 10;
cout << scoreAverage << endl;
switch(scoreAverage)
{
    case 10 : cout << "You got an A. Nice job!" << endl;
    case 9 : cout << "You got an A. Nice job!" << endl;
    case 8 : cout << "You got a B. Good job!" << endl;
    case 7 : cout << "You got a C. Decent job. Try studying more." << endl;
    case 6 : cout << "You got a D. Try studying more." << endl;
    case 5 : cout << "You got a F. If you need help, please let me know what's wrong." << endl;
    case 4 : cout << "You got a F. If you need help, please let me know what's wrong." << endl;
    case 3: cout << "You got a F. If you need help, please let me know what's wrong." << endl;
    case 2 : cout << "You got a F. If you need help, please let me know what's wrong." << endl;
    case 1 : cout << "You got a F. If you need help, please let me know what's wrong." << endl;
}

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i'm getting this output

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You got a C. Decent job. Try studying more.
You got a D. Try studying more.
You got a F. If you need help, please let me know what's wrong.
You got a F. If you need help, please let me know what's wrong.
You got a F. If you need help, please let me know what's wrong.
You got a F. If you need help, please let me know what's wrong.
You got a F. If you need help, please let me know what's wrong.

prime vale Sep 17, 2022, 11:48 PM

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you need to break;

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the switch "jumps" to the matching case, and executes everything from there to the end

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it "falls through" to the next case

lethal crow Sep 17, 2022, 11:49 PM

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would it look like this?

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case 10 : cout << "You got an A. Nice job!" << endl << break;

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or is that incorrect?

prime vale Sep 17, 2022, 11:49 PM

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break has nothing to do with iostreams

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it needs to be a separate statement

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break is a keyword, like switch and case, you can't send it to cout

lethal crow Sep 17, 2022, 11:51 PM

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where do i put it?

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wait i think i know

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i just pulled up a website

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i think this would be correct

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switch(scoreAverage)
{
case 10 :
cout << "You got an A. Nice job!" << endl;
break;

prime vale Sep 17, 2022, 11:54 PM

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yeah

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you can make use of this fall-through behavior, though

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you can write the stuff you want to happen in the F case just once

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like

case 4:
case 3:
case 2:
    std::cout << "4, 3, or 2!" << std::endl;
    break;

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the switch will jump to case 4:, do nothing, and continue until it hits the next break

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also, your original code behaved a little differently;
a score of 90-100 prints "You got an A. Nice job!",
a score > 100 prints "You did an amazing job!"

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your new code doesn't do that yet

signal orchidBOT Sep 19, 2022, 12:16 AM

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#Need help with switch statements