im trying a code to calculate accumulated/incremented amount of specific value.
for (int a=1; a<= qtydrink; a++)
{
cout << "enter drink name:"
cin.getline( drink, 15)
.......
if (strcmp(drink, "beer") == 0)
{
payment = 10.00;
.......
oke so one beer would cost 10$, but if the user input another beer, will it add or replace or something? i have an amount of 1.20 and user inputs it twice, amounting to 2.40 but in the output its just 2.20 sometimes.
i have 2 for loops. one for food and one for drinks. each time user can input different types of foods or drinks with different payments. i have to total up both food and drink's payment in the end plus tax.
please elaborate.
On the assumption that you are using payment as your output, that would be because you are setting the payment to be equal to 10.00, rather than incrementing it. To perform the increment, use += instead of =
EDIT: Everything you need to know about operators can be found here
Related
I'm looking at figuring out this program for a lab, I have been working on it for a while now, but cannot for the life of me figure out how this works.
The objective is to display an active equation as it decrements from from the initial value.
For example:
20000.00 + 83.33 - 150.00 = 19933.33
19933.33 + 83.06 - 150.00 = 19866.39
19866.39 + 82.78 - 150.00 = 19799.17
19799.17 + 82.50 - 150.00 = 19731.66
19731.66 + 82.22 - 150.00 = 19663.88
19663.88 + 81.93 - 150.00 = 19595.81
19595.81 + 81.65 - 150.00 = 19527.46
And so forth. I have to display that as an output on the screen. But am not sure how to keep a decrementing total like that and how to display it as an active equation like that in cout form.
The number on the far left is an initial loan that a user inputs, the number in the middle is the interest rate which is calculate using p*r/p (initial loan * interestrate(user will input this as well)/ initial loan). And the number on the right just before the equal sign is a payment which the usual will enter.
The goal is to get it to perform 10 iterations or once the initial loan is fully paid off whichever comes first.
Here is a little guidance
Finance
First you got your basics wrong. If this is finance and it looks this way :-), p*r/p is crap.
The second column in your plot is not a rate, neither is it an interest rate, it is an interest.
P is the loan ammount
r is an annual interest rate
The interest is calculated using P times r/12 since the payments you show are monthly in case r is entered mathematically (e.g. 0.05 for 5 %) or P*r/1200 in case r is counterconventional entered as percentage.
C++
The input of the parameters could be done e.g.
double P, r, q;
std::cout << "Enter P, q and r:\t";
std::cin >> P >> r >> q;
you will need to have the numbers printed fixed precision, this can by done with
std::cout << std::fixed << std::setprecision(2)
one last hint: The needed include files will be
#include <iostream>
#include <iomanip>
last you will need a loop have a look for for-loops or do-while loops.
This should help you to get your homework a good start.
I’m currently working on a project for my intro CS class. We are still pretty new to C++ and working with rudimentary concepts like while and for loops as well as file streams. The below problem is supposed to be resolved without resort to advanced features like arrays, vectors or functions.
Basically, I take a text file (FILE ONE) that has student and course data and create a new file. File one (where I’m inputting the data from) has 6k lines. Here’s an example below:
20424297 1139 CSCI 16000 W -1 3.00 RNL
20424297 1142 PSYCH 18000 W -1 3.00 RLA
20424297 1142 PSYCH 22000 W -1 3.00 RLA
20608974 1082 ENGL 12000 A- 3.7 3.00 RECR
20608974 1082 HIST 15200 B+ 3.3 3.00 FUSR
20608974 1082 PHILO 10100 A+ 4 3.00 FISR
See that very first column? Each unique set of numbers represents a student (also known as an eiD). File one is a giant list of every class a student took, and includes the subject, courses and grades they got.
The point of this project is to create a new text file that summarizes the GPAs of each student. That part I’m fairly confident I could figure out (taking cumulative GPA data). What confuses me is how I’m supposed to compare lines within the file to one another.
My professor did make things easy by having all the data grouped together by student. That lightens my load a little bit. I basically have to go through this file, line by line, and compare it with the next line to see if it has the same student ID number.
My first inclination was to create a series of nested while loops. The first loop would be active as long as data was being read. My next inclination was to repeat this in another loop. I would then create variables to hold the previous line’s student ID number and the current lines student ID number, creating conditions that would be active depending on whether or not they were the same or not:
while (sdStream2 >> eiD_2 >> semester_2 >> subject_2 >> coursenumSD_2 >> grade_2 >> gpa_2 >> courseHours2 >> code_2) // This loop will keep running until there's no data left
{
string eiD_base = eiD_2; // eiD_base was the variable I made to hold the "previous" student's ID, for comparison to the next line
while (sdStream2 >> eiD_2 >> semester_2 >> subject_2 >> coursenumSD_2 >> grade_2 >> gpa_2 >> courseHours2 >> code_2) // This loop unfortunately reads the entire file, defeating its intent
{
string eiD_temp = eiD_2; // eiD_temp was the variable I made to hold the current student ID, for comparison
if (eiD_base == eiD_temp)
{
outputStream2 << "Same line :( " << endl;
}
else
{
outputStream2 << eiD_2 << endl; // this is where you post the student data from the previous line!
}
}
}
After compiling and running the above, I came to the realization that this approach would not work because the second, nested loop, would run through every line in the FILE ONE without touching the first loop. I eventually figured out another method that used a counter instead:
// NOTE: The logic of the below code is as follows:
// Create a counter to note what the first student ID is.
// Store that value in eiD_Base when counter = 0. Increment counter.
// Now change eiD_Base everytime you find a line where eiD_temp
// differs from eiD_base.
string eiD_base;
string eiD_temp;
int counter = 0; // counter to help figure out what the first student ID was
while (sdStream2 >> eiD_2 >> semester_2 >> subject_2 >> coursenumSD_2 >> grade_2 >> gpa_2 >> courseHours2 >> code_2)
{
eiD_temp = eiD_2;
if (counter == 0)
{
eiD_base = eiD_2; // basically, set the first student ID to eiD_base when counter is 0. This counter is incremented only once.
counter++;
}
if (eiD_base == eiD_temp)
{
outputStream2 << "Same ID: " << eiD_2 << endl;
// NOTE: This is my first instinct as to where the code for calculating GPAs should go.
// The problem is that if that if the code is here, how do I factor in GPA data
// from a line that doesn't meet (eiD_base == eiD_temp)? I feel like that data would
// be jettisoned from calculations.
}
else
{
outputStream2 << "Previous ID: " << eiD_base << " and this is what eiD is now is now: " << eiD_temp << endl; // This is my first instict for
eiD_base = eiD_2; // if eiD_base !== eiD_temp, have eiD_base reset here.
}
}
That seemed closer to what I needed. However, I noticed another issue. With this method, when the variables I created to note changes in student id (eiD_base & eiD_temp) are not equal on a line of data, it seems like that line is jettisoned. Given that I need to calculate a number of things like GPA data for each student, having a method that doesn’t allow to accumulate data for the first line of a different student isn’t a good solution.
I don't know if I should dispense with the counter method entirely (in which case I would welcome recommendations of how best to replace it) or if my counter method is workable by placing the code for calculating GPAs more strategically. Any insight or help would be most welcome!
My answer style was my attempt of following: https://meta.stackexchange.com/questions/10811/how-do-i-ask-and-answer-homework-questions
A question you have is that you do not know if you should dispense with the counter method entirely (in which case you would welcome recommendations of how best to replace it) or if your counter method is workable by placing the code for calculating GPAs more strategically.
For the former, LiMuBei mentioned the method already. When you calculate more than one GPA (major gpa, gpa for just comp sci classes), you sum up the multiple GPA's with multiple variables.
For the latter, you would like to consider the unknown elements that vary the scenarios in each of the if/while statements. (counter == 0) is the scenario for the first line. (eiD_base == eiD_temp) is the scenario for the first line and the scenario when there are at least 2 lines, the current line has the same ID as the previous line. (eiD_base != eiD_temp) is the scenario when there are at least 2 lines, the current line has a different ID as the previous line. Here're the unknown elements: {1 line, at least 2 lines}, {sameID, differentID}. When the unknown element is {1 line}, you have to modify (counter == 0) and (eiD_base == eiD_temp). In (counter == 0), you modify the code that applies to the first and the only 1 line. In (eiD_base == eiD_temp), which applies to {1 line} and {at least 2 lines}, {sameID}, the code has to work for the 2 scenarios.
For the complete solution, you are going to declare variables before the while loop, aggregate variables in (eiD_base == eiD_temp), print the GPA values of the previous ID & set the variables for the first line of a new student in (eiD_base != eiD_temp), and print the GPA values of the last ID after the while loop.
double csci_Grape_Point;
// more variables for doing the calculation
while (sdStream2 >> eiD_2 >> semester_2 >> subject_2 >> coursenumSD_2 >> grade_2 >> gpa_2 >> courseHours2 >> code_2) {
eiD_temp = eiD_2;
if (counter == 0)
{
eiD_base = eiD_2;
counter++;
csci_Grape_Point = 0.0;
// more initialization of variables for doing the calculation
}
if (eiD_base == eiD_temp)
{
csci_Grape_Point = csci_Grape_Point + (gpa_2 * courseHours2);
// more sum calculation, such as total csci credit hours
}
else
{
outputStream2 << "Previous ID: " << eiD_base << " and this is what eiD is now is now: " << eiD_temp << endl;
eiD_base = eiD_2;
// for the previous ID, calculate gpa for just comp sci classes
// for the previous ID, calculate more gpa's
// set the variable to include the first line of data of a new student
csci_Grape_Point = (gpa_2 * courseHours2);
// set more variables for doing the calculation
}
}
// for the last ID, calculate gpa for just comp sci classes
// for the last ID, calculate more gpa's
Another question you have is about data calculation in (eiD_base == eiD_temp).
When a line doesn't meet (eiD_base == eiD_temp), the current line is different from the previous line. You factor in GPA data from the data you aggregate in (eiD_base == eiD_temp) and the data you set for the first line of a new student in (eiD_base != eiD_temp).
You probably want to solve a simpler problem first, with a file with 1 line and 2 lines, if the problem is not easily solved for you and you would like to attempt to do well in programming.
I wanted to write a program that returns how many months we could survive when we're given
our monthly expenditure, amount of disposable income, and interest rate (all in integers).
For instance, if we start with disposable income = 1000, interest rate = 5%, monthly expenditure = 100, then
after first month: 1000*1.05 - 100 = 950, we have 950 dollars left
after second month: = 950*1.05 - 100 = 897.5
and so on, and in the end, we can survive 14 months.
I wrote the following code in C++:
int main(){
int i=0;
int initialValue;
int interest;
int monthly;
double value=1.0*initialValue;
double r=1+1.0*interest/100;
while(value > 0){
if(value < monthly){
break;
}
else
{
value=value*r-monthly;
i++;
}
};
cout<<i;
return 0;
}
but for sufficiently large values of initialValue and small values of monthly, the program I wrote runs very slowly to the degree that it's unusable. Is there a problem with the code that makes it run not well (or very slow)?
Any help would be greatly appreciated.
double cannot store numbers precisely. One consequence of this is when you subtract a very small number from a very large number, the result is not changed from the original large value.
One solution to this problem is to use an int to do your calculations. Think of the values as the number of pennies, rather than the number of dollars.
A few notes:
The *1.0's are pointless. Instead, take advantage of implicit and explicit casts:
double value=initialValue;
double r=1+(double)interest/100;
++i is faster than i++.
value=value* can be rewritten as value*=.
You can mix the first two conditionals. Remove the if...break and change the while loop to while (value > 0 && value < monthly).
On the face of it, the reason this runs slowly is the large number of iterations. However, you didn't specify any specific numbers and I would expect this code to be able to execute at least a million iterations per second on any reasonably fast processor. Did you really expect to need to calculate more than 1 million months?
Apart from the novice style of the code, the underlying problem is the algorithm. There are very simple formulae for making these calculations, which you can find here: https://en.wikipedia.org/wiki/Compound_interest. Your situation is akin to paying off a loan, where running out of money equals loan paid off.
I'm new to C++ and was wondering if i was on the right track? I'm kind of confused about this but was hoping for possibly some helpful hints on things i am missing/ have wrong....i know its not completely finished i still need to do the breakdown of the dollars,quarters....etc
Question: A cash register uses an automated coin machine to help make change. We assume that a clerk is handed money to pay for purchases. For change, the clerk returns to the customer any paper money and directs the coin machine to distribute any changes less then $1. In this exercise, you are to simulate the action of the clerk and the machine.
At the cash register, we need access to the purchase price and the payment. The change, which is the difference between the payment and the purchase prices, is a real number. The whole part represents the change in dollars and the fractional part is the change in cents that is returned in quarters, dimes, nickels, and pennies. For instance, with a payment of $10 to cover purchases of $3.08, the required change is $6.92. The clerk hand out $6 and the coin machine distributes 3 quarters, 1 dime, 1 nickel, and 2 pennies for the 92 cents.
92 = 3(25) + 1(10) + 1(5) + 2
Use real-number objects that identify the purchase price (price), the amount of payment (payment), and the change (change). The main program computes the amount of change (coinChange) and partitions it into dollars (dollars), quarters (quarters), dimes (dimes), nickels (nickels), and pennies (pennies).
You must declare constants for quarters (quarters), dimes (dimes), nickels (nickels), and pennies (pennies). You must use compound operators in the calculations. You must use setreal(w,p) and setw(n) for the output.
What I have done so far:
// Me
// A BRIEF PROGRAM DESCRIPTION FOR CHAPTER 2, HOMEWORK 4
// COMMENT THE PREPROCESSOR
#include <iostream.h>
// COMMENT THE PREPROCESSOR STATEMENT
#include "textlib.h"
int main( )
{
// COMMENT THE CONSTANTS
const int QUARTER_AMOUNT = 25;
const int DIME_AMOUNT = 10;
// COMMENT THE OBJECTS
double price;
double payment;
double change;
int numofDollars;
int numofQuarters;
int numofDimes;
int numofNickles;
int numofPennies;
int coinChange;
cout << "Enter the purchase total: ";
cin >> price;
cout << "Enter the payment: $";
cin >> payment;
// COMMENT THE CALCULATION
change = payment - price;
numofDollars = int(change);
coinChange = (int((change / numofDollars) * 100));
numofQuarters = coinChange / 25;
coinChange = coinChange / (numofQuarters * 25);
numofDimes = coinChange / 10;
numofNickles = coinChange / 5;
numofPennies = coinChange / 1;
// OUTPUT THE INFORMATION
return 0;
}
Yes, you are on the right track. Your general structure is sound. These sorts of homework assignments almost always have a structure like this:
int main () {
// read in the data
...
// Do the math
...
// Write out the data
...
}
You do have some math errors. Try stepping through the code with a pencil and paper, pretending that you are the computer. Also, try stepping through the code with your debugger, examining the variables after each line. Compare what actually happened to what you expected.
Assume you are given three variables, revenue, expenses, and profit, all of type Money (a structured type with two int fields, dollars and cents). Assign to profit the result of subtracting expenses from revenue. Let's make the happy assumption that revenue exceeds expenses. However you still may find that the cents part of expenses exceeds that of revenue. If that is the case you will have to "borrow" 1 from revenue dollars (i.e. subtract 1) and "give" it to revenue's cents (i.e. add 100!) in order to carry out the subtraction properly.
Here is what I have but it's not working:
if (revenue.cents < expenses.cents)
{
revenue.dollars = revenue.dollars -1;
revenue.cents = revenue.cents + 100;
profit = revenue - expenses;
}
else
{
profit = revenue - expenses;
}
I get this error message:
error: no match for 'operator-' in 'revenue - expenses'
Any help is appreciated. Thanks.
You're getting that error because you cannot subtract one structure from another. You will have to define an operator-() function for your struct.
You need to call each element of the structure and subtract them separately. MyProgLab will not allow you to define a function for this exercise. Not only that but if you enter the code that you have above it will tell you that 'you were not supposed to modify the element'. In order to avoid this you must conduct the borrowing of the dollar inside the arithmetic.
Like this:
if(expenses.cents > revenue.cents)
{
profit.dollars = (revenue.dollars - 1) - expenses.dollars;
profit.cents = (revenue.cents + 100) - expenses.cents;
}//end if