Why i'm getting overflow? - c++

I'm very new to c++ and still in the process of learning it.
I've been assigned to create a simple bank simulator and just stumble upon a problem i can't seem to figure out for some reason.
Whenever i try to check the balance it shows me some numbers and letters and my first thought was either it showed the memory adress or a overflow.
I could deposit something first and it will be added to the balance variable and shows up in the program aswell without some awkward numbers and letters. My goal is to make sure that the balance is always showing a 0 until the user deposit or withdraw from it.
I somehow managed to fix this by using float instead of double, I'm not really sure why it worked at this point since I'm way to tired to even think about it, but I would rather use double since this program might use more data.
If anything seems unclear of what I'm trying to say I'll try and answer your question as soon as I can. I also add a image here to show you what I'm talking about.
#include <iostream>
using namespace std;
int main()
{
while(true){
cout << "[D]eposit\n";
cout << "[W]ithdrawal\n";
cout << "[B]alance\n";
cout << "[I]nterest payment\n";
cout << "[E]xit\n";
char menu;
double balance, deposit, withdraw;
cin >> menu;
switch(menu)
{
case'D':
cout << "[DEPOSIT]\n" << "Deposit: ";
cin >> deposit;
balance += deposit;
continue;
case'W':
cout <<"[WITHDRAWAL]\n" << "Withdraw: ";
cin >> withdraw;
balance -= withdraw;
continue;
case'B':
cout << "[BALANCE]\n" << "Amount: " << balance;
continue;
case'I':
cout << "[INTEREST PAYMENT]\n";
continue;
case 'E':
cout << "Program is closing...";
break;
default:
cout << "Please use uppercase letters";
continue;
}
break;
}
return 0;
}

Balance isn't initialized, so when you add / substract an amount, the result is odd due to the random initial value of balance.

Well the main reason for getting the gibberish data is because your balance variable is uninitialized, and accessing it is undefined behaviour.
You can fix it by doing this:
double balance = 0;
double deposit, withdraw;
Also, your program won't work as expected because you declare the balance variable inside the while loop. Just declaring the variables outside the loop will make it work as expected.
double balance = 0;
double deposit, withdraw;
while(true){
...
}

Related

How do I calculate and display the correct percentage?

I am a C++ noob.
I am trying to work on this text-based game for school, and I am having trouble with displaying the correct percentage. I think this has to do with how I calculate it in the program, or I am screwing something up with the function.
I would be most grateful for some assistance. Cheers.
#include <string>
#include <cmath>
#include <iostream>
using namespace std;
double menu (float crew_count);
double calculatePct(float crew_count, float number_of_deaths)
{
double percent = ((crew_count - number_of_deaths) / crew_count) * 100;
}
double welcome ()
{
int crew_count;
string backstory = "\nYou are in charge of a top-secret military mission, when your\nspace ship makes an emergency landing, on the largest moon of planet Gork.\nThe space ship is damaged. Oxygen levels begin to drop.\nHow many military personnel are on your ship?\nNumber of personnel: ";
cout << backstory;
cin >> crew_count;
if (crew_count >= 1)
menu(crew_count);
else if (crew_count < 1)
cout << "\nThere must be 1 or more members of the crew! Please enter a valid number!\n";
}
double menu (float crew_count)
{
double percent;
double main_option;
cout << "\nChoose one:\n1. Attempt repairs on the ship.\n2. Request an emergency rescue from mission command.\n3. Break protocol and reveal the top-secret space ship's location,\nto the Russians on a nearby moon, asking for their assistance.\nYour choice: ";
cin >> main_option;
if (main_option == 1)
{
cout << "\nToxic material on the moon has corroded the launch gear, and the \nlaunch exploded!\n\nThere were no survivors.\n";
}
else if (main_option == 2)
{
cout << "\nThe oxygen was depleted before the rescue team arrived.\nThere were 4 people killed.\n";
if (crew_count <=4)
cout << "0% of crew members were rescued!\n";
else
float percent = calculatePct(crew_count, 4);
cout << percent << "% of the crew was rescued.\n";
}
else if (main_option == 3)
{
cout << "\nThe Russians agree to send a rescue ship, but secretly attempt to hack into the ships systems remotely, which triggers an automatic shut down of all\ncommunications systems and locks all mission critical storage units, including\none of the storage unit that holds emergency oxygen tanks.\n\nOne quarter of all personnel are lost.\n";
}
else if (main_option != 1, 2, 3)
{
cout << "\nYou have been eaten by a Grue!\n";
}
}
int main()
{
cout << "Welcome to Gork 1.0\nCreated by Cortez Phenix\nTo make selections, enter the number of each option!\n\n";
int choice;
cout << "What would you like to do?\n1. Play Game\n2. Exit\nYour Choice: ";
cin >> choice;
if (choice == 1)
welcome();
else if (choice == 2)
cout << "\nGoodbye!\n";
else
cout << "\nPlease choose 1 or 2.\n";
return 0;
}
Excuse me. I'm sure this post is hectic.
IMAGE: At the bottom, you can see the queer number
If we do some slight reformatting on parts of your code, it looks like this:
if (crew_count <=4)
cout << "0% of crew members were rescued!\n";
else
float percent = calculatePct(crew_count, 4);
cout << percent << "% of the crew was rescued.\n";
The value you print is not the value calculated by calculatePct, it's the indeterminate value of the percent variable defined earlier in the function.
In short: You forgot your curly-braces:
if (crew_count <=4)
cout << "0% of crew members were rescued!\n";
else
{ // Note curly brace here
float percent = calculatePct(crew_count, 4);
cout << percent << "% of the crew was rescued.\n";
} // And also here
I recommend you enable more verbose warnings, as the compiler should be able to detect that you use the uninitialized variable, as well as the new variable being initialized but not used.
you mixed intergers and floats and void
int crew_count then you fed double menu(float crew_count).
your menu function doesnt return anything its supossed to be void so does your welcome function
Also you calculatePct does not return the calculated percentage. Do that by adding return percent;
See if it helps

For Loops (C++)

Assignment:
The program should ask the user to enter a positive number and display all numbers from 1 to the input value. If the number is not positive, an error message should show up asking the user to re - enter the number.
My specific problem:
For my program, if the user enters an incorrect number and then re - enters a positive number, it does not display all the numbers from 1 to the input value. The program just ends.
#include <iostream>
using namespace std;
int main()
{
int userChoice;
int i = 1;
cout << "Enter a positive integer" << endl;
cin >> userChoice;
if (userChoice > 0)
{
for (i = 1; i <= userChoice; i++)
{
cout << "Loop 1:" << endl;
cout << i << endl;
}
}
else if (userChoice < 0)
cout << "Please re - enter" << endl;
cin >> userChoice;
system("pause");
return 0;
}
You need some sort of loop at the top of your program, that keeps asking for input until the user provides something valid. It looks like a homework assignment, so I will provide pseudo-code, not something exact:
std::cout << "Enter a number:\n";
std::cin >> choice;
while (choice wasn't valid) { // 1
tell the user something went wrong // 2
ask again for input in basically the same way as above // 3
}
// after this, go ahead with your for loop
It is actually possible to avoid the duplication here for step 3, but I worry that might be a little confusing for you, so one duplicated line really isn't such a big problem.
As an aside, you may wish to reconsider your use of what are often considered bad practices: using namespace std; and endl. (Disclaimer - these are opinions, not hard facts).

cin not accepting user input in C++

I'm a beginner in programming, and I'm trying to make a program that calculated how much radiation you've been exposed to throughout your life. For some reason, the 'cin' in my xray function doesn't accept user input, and just exits with code 0.
#include <iostream>
#include <conio.h>
#include <windows.h>
#include <stdlib.h>
#include <string>
#include <sstream>
using namespace std;
bool nearpowerplant;
int XRay; // the amount of times you got an x-ray
double tRads = 0; // your total dose of radiation in your lifetime, measured in mSv (millisievert)
int age;
//the sleep function
void sleep() {
Sleep(1000); // 1000 miliseconds = 1 second
}
/*
>system("CLS")< for clear the console
*/
//introduction and pretty much the menu
void intro() {
cout << "Welcome to the Radiation Level Calculator" << endl;
sleep();
cout << "Conceptualized and created by Anatoly Zavyalov" << endl;
sleep();
cout << "Press the ENTER key to begin." << endl;
cin.get();
}
//introduction to general questions
void genintro() {
// intro to the medical
system("CLS");
sleep();
cout << "Let's begin with general questions." << endl;
sleep();
cout << "Press the ENTER key to continue." << endl;
cin.get();
}
//medical questions
void Age() {
//age
system("CLS");
cout << "How old are you?\n" << endl;
sleep();
cin >> age;
if (age <= 0) {
cout << "Your age can't be less or equal to 0." << endl;
Age();
}
else {
tRads += (age * 2);
sleep();
cout << tRads << endl;
}
}
//live close to powerplant?
void powerplant() {
system("CLS");
cout << "Do you live within 75 kilometers of a nuclear powerplant?" << endl;
sleep();
cout << "If yes, type YES. If no, type NO." << endl;
cin >> nearpowerplant;
if (nearpowerplant = "YES") {
tRads += (age * 0.01);
}
else {}
sleep();
cout << tRads << endl;
}
void xray() {
system("CLS");
cout << "How many times have you had an x-ray?\n" << endl;
sleep();
cin >> XRay;
if (XRay < 0) {
cout << "You can't have an x-ray a negative amount of times." << endl;
}
else {
tRads += (XRay * 3.1);
}
sleep();
cout << tRads << endl;
}
//main function, put all of the loops into here
int main() {
intro(); // the introduction
genintro(); // medical intro
Age(); // asks for age
powerplant(); // asks if lives close to powerplant
xray(); // asks for x-ray
return 0;
}
EDIT: I have edited the post to include the whole code. By the way, I am using Visual Studio Community 2017.
bool nearpowerplant;
nearpowerplant is a bool. It is true or false. That is it. It's worth noting that there is no reason for this variable to be globally accessible and consuming storage for the entire run of the program. It is used twice in the program, both times in the same function. It should be an Automatic variable scoped by the function that uses it.
cout << "If yes, type YES. If no, type NO." << endl;
cin >> nearpowerplant;
Reading "YES" or "NO" into a variable of type bool fails. cin cannot convert the string input into a boolean value and cin stops accepting input until the error is cleared. It's also a good idea to remove the garbage input that caused cin to fail or guess what? cin's just going to fail again. There are hundreds of SO questions on how to handle this, so I'm just going to drop keywords here: clear and ignore.
Takeaways: Make sure the data entry matches the type of the data being entered into and test the stream after every read to make sure the read succeeded.
eg:
if (cin >> nearpowerplant)
{
// do stuff
}
else
{
// clean up
}
This solves OP's visible error, but since it is heavily entwined with the next bug they are likely to find, we might as well cover it as well.
if (nearpowerplant = "YES") {
tRads += (age * 0.01);
}
else {}
if (nearpowerplant = "YES") { uses = (assignment) where it should use == (comparison). C++ is unforgiving here because this will compile. What it really did was takes the address of the string literal "YES", test that it's not null, and set nearpowerplant to the result. Since the address of the string literal is never going to be NULL, the result is always true, and when the if tests the result, the if will always enter.
Eg: http://ideone.com/4QL2jn
So what we need is something more like
cout << "If yes, type YES. If no, type NO." << endl;
string temp;
cin >> temp;
if (temp == "YES") {
tRads += (age * 0.01);
}
else {}
Note this will skip if the user inputs "yes", "y", "Yes" or anything other than exactly "YES". How you deal with this is up to you, but std::tolower and std::transform may help somewhat.
I think with sleep() comes undefined behavior, you should test it without, the os handles user-input and you do not have to care about the user typing in. endl flushes cout, so the text is directly shown.
Edit:
Maybe system("CLS") or sleep produces a silent error.

How to assign an enum value to a double variable defined by the user ?? C++

Hello i am a student so i wanted to say sorry in case my writing is tiring, feel free to correct me .
i am having the following problem i am trying to assign an enum int value to another double variable to make one multiplication.
so the variable costOfRoom should take the value D or T or S which belong to an enum. (D=200 ,T=150,S=110)
this must be done by the user .
But cant find any way , i tried to make the second variable a string type but its not working again. it will just take the chars normally as a string would do :(
Also tried cin >> type_Ofroom costofroom ;
but i think that this is used in Java??
Searched the forum also haven't any similar answer :(
The program runs fine it doesn't have any compiling errors :)
Thanks for your time
/* build a software system which will allow a hotel receptionist,
to enter in bookings for guests who come to the desk.
The system should display the room options as:
Room Price Code
---------------------------------------------------------------
Deluxe Room £200 D
Twin Room £150 T
Single £110 S
The receptionist should be prompted to enter in the room type and the number of
nights a guest wishes to stay for and then calculate the amount
they need to pay.
*/
// solution
#include <iostream>
using namespace std;
int main() {
// decleration of variables
double number_OfDays = 0, Totalcost = 0, costofroom = 0;
enum type_Ofroom { D = 200, T = 150, S = 150 };
cout << "enter the type of the room " << endl << endl;
//input of room type
cin >> costofroom; // **here is the problem** i am trying to give the
// values of the enum varaiable
// it should have D or T or S but i cant make it
cout << "enter the number of the days " << endl << endl;
//input of days
cin >> number_OfDays;
// calculation
Totalcost = costofroom * number_OfDays;
// result
cout << "the costumer has to pay " << Totalcost << " pounds" << endl << endl;
return 0;
}
You can read into a double, and then check against your enum values:
//input of room type
while (1)
{
cin >> costofroom;
if (costofroom == 0.0)
costofroom = D;
else if (costofroom == 1.0)
costofroom = T;
else if (costofroom == 2.0)
costofroom = S;
else
{
cout << "You didn't enter a valid option" << endl;
continue;
}
break;
}
However, it would be better to read into an int, and then set your double afterward.
double costofroom;
int option;
...
//input of room type
while (1)
{
cin >> option;
if (option == 0)
costofroom = D;
else if (option == 1)
costofroom = T;
else if (option == 2)
costofroom = S;
else
{
cout << "You didn't enter a valid option" << endl;
continue;
}
break;
}
The user can only input characters. cin will convert groupings of numbers to an int (e.g. 123) or or double (e.g. 123.5). It will also handle non-numeric groupings to std::strings (e.g. hello) or individual characters (e.g. c).
Once you have the user's input, you can convert them to your enum. You can use if statements, case statements or some type of table look up to do this.

Why is exit(0); giving me a std:string... error?

I'm new to C++. I decided to not watch the next tutorial and put my skills to use, by making a funny Mind Reader application. I'm pleased with myself, however, even though I've ironed out most bugs, I still have one concerning the exit function. I read the C++ documentation for it, and I'm not sure what I did wrong. I did exit(0);. I have a very weird error, which is:
no match for call to '(std::string {aka std::basic_string<char>}) (int)
I have searched online, however I am still unaware of what the problem is. My error is on line 59 (marked in the code):
#include <iostream>
#include <string>
#include <cstdlib>
using namespace std;
int main()
{
//declaring variables to be used later
string name;
string country;
int age;
//header goes below
cout << "#######################################";
" ############ MIND READER ############"
"#######################################\n\n";
//asks if the user would like to continue and in not, terminates
cout << "Would like you to have your mind read? Enter y for yes and n for no." << endl;
cout << "If you do not choose to proceed, this program will terminate." << endl;
string exitOrNot;
//receives user's input
cin >> exitOrNot;
//deals with input if it is 'y'
if (exitOrNot == "y"){
cout << "Okay, first you will need to sync your mind with this program. You will have to answer the following questions to synchronise.\n\n";
//asks questions
cout << "Firstly, please enter your full name, with correct capitalisation:\n\n";
cin >> name;
cout << "Now please enter the country you are in at the moment:\n\n";
cin >> country;
cout << "This will be the final question; please provide your age:\n\n";
cin >> age;
//asks the user to start the sync
cout << "There is enough information to start synchronisation. Enter p to start the sync...\n\n";
string proceed;
cin >> proceed;
//checks to see if to proceed and does so
if (proceed == "p"){
//provides results of mind read
cout << "Sync complete." << endl;
cout << "Your mind has been synced and read.\n\n";
cout << "However, due to too much interference, only limited data was aquired from your mind." << endl;
cout << "Here is what was read from your mind:\n\n";
//puts variables in sentence
cout << "Your name is " << name << " and you are " << age << " years old. You are based in " << country << "." << endl << "\n\n";
cout << "Thanks for using Mind Reader, have a nice day. Enter e to exit." << endl;
//terminates the program the program
string exit;
cin >> exit;
if (exit == "e"){
exit(0); // <------------- LINE 59
}
}
}
//terminates the program if the input is 'n'
if (exitOrNot == "n"){
exit(0);
}
return 0;
}
Thanks
The local variable exit shadows other identifiers from outer scopes with the same name.
To illustrate with a smaller example:
int main()
{
int i;
{
int i;
i = 0; // assign to the "nearest" i
// the other i cannot be reached from this scope
}
}
Since the only exit visible is an object of type std::string, the compiler sees exit(0) as a call to operator()(int) and throws a hissy fit when it doesn't find one among std::string members.
You can either qualify the name (std::exit(0);) or rename the variable. And since all of your code is in main you can simply say return 0; instead.
Try using return 0; or return EXIT_SUCCESS;. It's the exact same thing. Also, you can only input one word into a cin. Instead, use getline(cin, string name); If it still doesn't work, add a cin.ignore(); before your getline(cin, string name);, like this:
//stuff
string country;
cout << "Now please enter the country you are in at the moment:\n\n";
cin.ignore();
getline(cin, country);
//stuff
return 0;
The problem is arrising because you declared a standard keyword as the name of a local variable.
Now as the local variable is of type sting it is not able to take it as its value.