A minor problem with a menu code
There's really no errors in this code, but I do want to make it better. As seen below in the code, I have the customer enter in "5 0" to end the code, is there a way to just let them enter just one number instead of two? Thanks!
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It's seems like huge but you can do it by using switch , i suggest you to use switch case according to your display..
you can do like ,In switch other than number in choice it will terminate the loop .
you can do like ,In switch other than number in choice it will terminate the loop .
There is a lot of repeated code in your program. Any time you see repeated code, that is a good indication you should move that code into a function.
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This code worked out nicely! But can you explain how bool, repeats, voids, and breaks work? Thanks! Also I do want the qty cumulative, how do you do that?
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bool is a built in type that has two possible values: true or false. get_item uses a bool return value to determine if the loop at line 79 should continue or not. If get_item returns true, get_item gets called again. if get_item returns false, the while condition is not satisfied and the loop ends.
repeat is used to control the loop from lines 28-44. The purpose of the loop is to check that we have valid input. If we don't have valid input, we set repeat to true, and the will execute another iteration of the loop. If we have valid input, then repeat remains false, and the loop terminates.
void says a function returns nothing.
If you don;t use break in a switch statement, you will fall through to the next case.
I'll let you make an attempt to do that. Hint: Look at line 49
repeat is used to control the loop from lines 28-44. The purpose of the loop is to check that we have valid input. If we don't have valid input, we set repeat to true, and the will execute another iteration of the loop. If we have valid input, then repeat remains false, and the loop terminates.
void says a function returns nothing.
If you don;t use break in a switch statement, you will fall through to the next case.
| I do want the qty cumulative, how do you do that? |
I'll let you make an attempt to do that. Hint: Look at line 49
Hmm, if that's the case, why would you put repeat = false before you tell it that item = 5 is false? And what does return 0 has to do there?
Also, why would you code it items[item-1]? Is there a difference if you just code it into a number? Or set it to just items[item]?
And I tried qty += qty, it didn't work :/
Sorry for the many questions, but why would items[4] come after int main?
For line 74, you only set items[4] to 0, how did that initialize all numbers to 0? And for it, why did you use { rather than [? Or without brackets rather?
But I really appreciate your help, thanks :)
Also, why would you code it items[item-1]? Is there a difference if you just code it into a number? Or set it to just items[item]?
And I tried qty += qty, it didn't work :/
Sorry for the many questions, but why would items[4] come after int main?
For line 74, you only set items[4] to 0, how did that initialize all numbers to 0? And for it, why did you use { rather than [? Or without brackets rather?
But I really appreciate your help, thanks :)
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| why would you put repeat = false before you tell it that item = 5 is false? |
At line 29, we set repeat to false at the top of the loop. We're going to assume the user entered valid data. In the default branch of the switch statement, we set repeat to true if we detect invalid data. We could have set repeat to true initially, but then we would have had to set it to false in each of the 4 valid branches in the switch statement. Easier to change it just once.
We could have put the repeat = false after the test for 5. That would not change the logic. Just a matter of style to set variables at the top of the loop before any transfers of control. Less chance of possible logic errors.
The do/while loop is not actually needed. We could remove the loop by changing line 43 to
return true; That would cause us to call get_item again. Again a matter of style. I prefer not to return from get_item until I actually have an item or no more are wanted (two conditions). The loop at line 79 current has a null action, but if we were to add code there, we might have to distinguish between whether get_item actually obtained an item or not, or no more are wanted (three conditions). The do/while loop is a common idiom for checking for valid input and is something you should learn, which is why I used it.| Also, why would you code it items[item-1]? Is there a difference if you just code it into a number? Or set it to just items[item]? |
The user enters an item number from 1 to 4. However, the elements in our array from 0-3, therefore we subtract 1 to refer to the correct element.
| And I tried qty += qty, it didn't work |
That would just double the qty the user entered. Again, look at line 49. How would you change it so that you're adding qty to the value already in the array?
| why would items[4] come after int main? |
You have to declare the items array somewhere. The choices are global or local to main. Declaring globals is poor style. Variables should always be as local as possible.
| For line 74, you only set items[4] to 0, how did that initialize all numbers to 0? And for it, why did you use { rather than [? |
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That line has two parts. The left side of the = declares an array of 4 ints. The right side of the array is initialization syntax. The {0} (with braces) says to initialize the array of its declared size to zeroes.
Oh okay I see; in class, we just haven't learned any loop statements yet, so I have a lot of questions. As for the arrays, does it always default set it to 0-3? Or can we change it to items[item] and then items[1] = salad, items[2]=soups etc, pretty much just skipping out 0 is what I mean. As for the cumulative quantity, I figured it out, I just didn't realize that the numbers were stored into the arrays, thanks :)
| does it always default set it to 0-3? |
As I said before, the
= {0} initialization syntax sets the entire array to 0.| Or can we change it to items[item] |
No. item is the item number the user entered. You don't want to declare the dimension of an array based on the item number the user entered. Besides, variable array dimensions are not legal in C++.
| and then items[1] = salad |
You could do that to avoid subtracting 1 from item. You would have to declare items as
int items[5]; to allow you to reference entries 1-4 and ignore the 0th entry.
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