My prototype doesn't work, probably cause I'm unable to do the referencing of values properly. I'm trying to add a function called num_pos to return number of even values entered but I have no idea where to start
#include <iostream>
using namespace std;
void entry(double arry[],int size);
//Additional function prototype when needed
void displayEntry(double dtAry[],int sz) ;
int main()
{
int size = 6;
double values[6];
cout << "Data Analysis" << endl;
cout << "=============" << endl<<endl;
entry(values, 6);// Call function to allow user to enter the readings
// Additional function calls when needed
return 0;
}
// Your function implementaiton here
void entry(double arry[],int size)
{
int i;
for(i=0;i<size;i++)
{
cout << "Enter Reading " << i+1 << ": ";
cin>> arry[i];
}
return;
}
void displayEntry(double dtAry[],int sz)
{
cout <<"You have entered the following readings: ";
for(int i=0;i<sz-1;i++)
{
cout << dtAry[i] <<", ";
}
}
Related
The objective is to output the same data as the first program.
The first program requires manual input of the room number and room cost. The second (problematic) program requires it to auto populate with the room number and room cost being hard coded in to an array within the main.
A default constructor of the class "room" is needed to populate the array and add setter functions to set the values of the room number and cost.
The objective of the whole program is to create the array, populate with test data and then list the data about the rooms.
Program 1 (manual in put) - this works fine;
#include<iostream>
using namespace std;
class room
{
int roomNo;
float roomCost;
public:
void GetData ();
void PutData ();
};
void room::GetData ()
{
cout << "\n\tEnter room number : ";
cin >> roomNo;
cout << "\n\tEnter room cost : ";
cin >> roomCost;
}
void room::PutData ()
{
cout << "\n\t\t\t" << roomNo << " \t|\t " << roomCost;
}
int main ()
{
int roomNo;
room roomList[10];
for (roomNo = 0; roomNo < 10; roomNo++)
{
cout << "\nEnter details of " << roomNo + 1 << " room" << endl;
roomList[roomNo].GetData ();
}
cout <<"\n*******************************************************************************";
cout << "\n\t\t\t Room Details";
cout <<"\n*******************************************************************************";
cout << "\n\t\t Room Number \t| Cost per Night";
cout << "\n\t\t--------------------------------------";
for (roomNo = 0; roomNo < 2; roomNo++)
roomList[roomNo].PutData();
getchar ();
getchar ();
}
Second (problematic) program;
#include<iostream>
using namespace std;
class room
{
int roomNo;
float roomCost;
public:
room();
void PutData ();
};
room::room()
{
cout<<"\n\t\t\t"<<roomNo<<" \t|\t "<<roomCost;
}
void room::PutData ()
{
cout << "\n\t\t\t" << roomNo << " \t|\t " << roomCost;
}
int main ()
{
int roomNo[10] = {1,2,3,4,5,6,7,8,9,10};
float roomCost[10] = {100.00, 90.00, 85.50, 80.00, 80.00, 50.00, 50.00, 45.50, 45.50, 40.00};
room roomList[10]; //Statement 3 : Creating Array of 3 Employees
cout <<"\n*******************************************************************************";
cout << "\n\t\t\t Room Details";
cout <<"\n*******************************************************************************";
cout << "\n\t\t Room Number \t| Cost per Night";
cout << "\n\t\t--------------------------------------";
for (int roomNo = 0; roomNo < 10; roomNo++)
roomList[roomNo].PutData();
getchar ();
getchar ();
}
The problem is that roomNo and roomCost never actually get set to anything for each room instance. The class won't automatically pull from the arrays you define in main.
Additionally,
roomList[roomNo].PutData();
Accesses uninitialized data:
void room::PutData ()
{
cout << "\n\t\t\t" << roomNo << " \t|\t " << roomCost;
}
(The constructor has the same problem)
The solution is to initialize each room with the correct data. I recommend using the constructor:
room(int _roomNum, float _roomCost) : roomNo(_roomNum), roomCost(_roomCost)
{}
Then use a vector to initialize (instead of room roomsList[10])
std::vector<room> rooms;
rooms.reserve(10);
for(size_t i = 0; i < 10; ++i)
rooms.emplace_back(roomNo[i], roomCost[i]);
Live Demo
You should have two setters, one for each member, and then write your loop like
for (int n = 0; n < 10; n++)
{
roomList[n].setNumber(roomNo[n]);
roomList[n].setCost(roomCost[n]);
}
(On a side note, you should do the same with the first program and handle user input in main.)
I've come across a little problem, how do I print the winning candidate's name? See the instructions here are, input five names, their number of votes and percentage of votes, whoever has the highest wins. I don't know if I did my code right, but it works.. well except for the name part. I've tried everything from a lot of for loops to transfer the array or what.
I'm almost done with the code.
Here's the code
#include <iostream>
#include <stdio.h>
using namespace std;
int main()
{
char candidates[50];
int votes[5]={0};
float percent[5]={0};
int a,b,c,d,e,i;
int maxx;
int champ=0;
char winner[50];
cout << "Enter the candidates' last names: ";
cout << endl;
for(a=1;a<=5;a++)
{
cout << a << ". ";
cin >> candidates;
}
cout << endl;
cout << "Enter their number of votes: " << endl;
for(b=1;b<=5;b++)
{
cout << b << ". ";
cin >> votes[b];
}
cout << endl;
cout << "percentage of votes: " << endl;
for(c=1;c<=5;c++)
{
cout << c << ". ";
percent[c]=votes[c]*0.2;
printf("%.2f\n", percent[c]);
}
cout <<"Candidates\t\tVotes\t\t% of Votes" << endl;
for(int k=1;k<=5;k++)
{
cout << candidates[k] << "\t\t\t" << votes[k] << "\t\t\t";
printf("%.2f\n", percent[k]);
}
maxx=percent[0];
for(d=1;d<=5;d++)
{
if(maxx<percent[d]);
{
//what happens here?
}
}
return 0;
}
You should keep a 2d array of characters or array of string for storing candidate names instead of a 1-d array.
char candidates[5][10]; //
for(int i = 0; i < 5; i++)
{
cin >> candidates[i];
}
Then keep a variable to store index for winning candidate
int winIndex = 0;
int winPercent = 0;
for(int i = 0; i < 5; i++)
{
if(percent[i] > winPercent)
{
winPercent = percent;
winIndex = i;
}
}
Finally print name of winning candidate;
cout << candidates[winIndex];
In object oriented approach, you may create a class with following information
class Candidate
{
string name;
int votes;
float percent;
};
Use string candidates[50]; instead of char candidates[50];
then cin >> candidates[a];
I'm an absolute beginner in c++. Literally. It's just been a week.
Today I was writing a program to test how many iterations are needed to make a certain number palindromic.
Here is the code:
#include <iostream>
#include <string>
#include <algorithm>
/* This program calculates the steps needed
to make a certain number palindromic.
It is designed to output the values for
numbers 1 to 1000
*/
using namespace std;
class number
{
public:
string value;
void reverse();
};
void number::reverse()
{
std::reverse(value.begin(),value.end());
}
void palindrome(number num)
{
string n=num.value;
number reversenum, numsum, numsumreverse;
reversenum=num;
reversenum.reverse();
numsum.value=num.value;
numsumreverse.value=numsum.value;
numsumreverse.reverse();
int i=0;
while (numsum.value.compare(numsumreverse.value) !=0)
{
reversenum=num;
reversenum.reverse();
numsum.value=to_string(stoll(num.value,0,10)+stoll(reversenum.value,0,10));
numsumreverse.value=numsum.value;
numsumreverse.reverse();
num.value=numsum.value;
i++;
}
cout << "The number " << n << " becomes palindromic after " << i << " steps : " << num.value << endl;
}
int main()
{
number temp;
int i;
for (i=1; i<1001; i++)
{
temp.value=to_string(i);
palindrome(temp);
}
return 0;
}
It goes on smooth for numbers upto 195. But, in case of 196 I get an error.
It says:
terminate called after throwing an instance of 'std::out_of_range'
what(): stoll
I cannot make out what to do. I tried starting from 196 but the error persisted. Any help will be greatly appreciated. :)
UPDATE: This time I tried to do it using ttmath library. But arghs! It again stops at 195 and doesn't even report an error! I might be doing something foolish. Any comments would be appreciated. Here's the updated code:
#include <iostream>
#include <string>
#include <algorithm>
#include <ttmath/ttmath.h>
/* This program calculates the steps needed
to make a certain number palindromic.
It is designed to output the values for
numbers 1 to 1000
*/
using namespace std;
class number
{
public:
string value;
void reverse();
};
void number::reverse()
{
std::reverse(value.begin(),value.end());
}
template <typename NumTy>
string String(const NumTy& Num)
{
stringstream StrStream;
StrStream << Num;
return (StrStream.str());
}
void palindrome(number num)
{
string n=num.value;
number reversenum, numsum, numsumreverse;
reversenum=num;
reversenum.reverse();
numsum.value=num.value;
numsumreverse.value=numsum.value;
numsumreverse.reverse();
ttmath::UInt<100> tempsum, numint, reversenumint;
int i=0;
while (numsum.value.compare(numsumreverse.value) !=0)
{
reversenum=num;
reversenum.reverse();
numint=num.value;
reversenumint=reversenum.value;
tempsum=numint+reversenumint;
numsum.value=String<ttmath::UInt<100> >(tempsum);
numsumreverse.value=numsum.value;
numsumreverse.reverse();
num.value=numsum.value;
i++;
}
cout << "The number " << n << " becomes palindromic after " << i << " steps : " << num.value << endl;
}
int main()
{
number temp;
int i;
for (i=196; i<1001; i++)
{
temp.value=to_string(i);
palindrome(temp);
}
return 0;
}
UPDATE: It's solved. Some research suggested that 196 might be a Lychrel Number. And the result I was getting after implying the ttmath library is just reassuring that my algorithm works. I have tried it out for all the numbers upto 10000 and it gave out the perfect results. Here is the final code:
#include <iostream>
#include <string>
#include <algorithm>
#include <ttmath/ttmath.h>
#include <limits>
/* This program calculates the steps needed
to make a certain number palindromic.
It is designed to output the values for
numbers inside a desired range
*/
using namespace std;
string LychrelList;
int LychrelCount=0;
class number
{
public:
string value;
void reverse();
};
void number::reverse()
{
std::reverse(value.begin(),value.end());
}
template <typename NumTy>
string String(const NumTy& Num)
{
stringstream StrStream;
StrStream << Num;
return (StrStream.str());
}
void palindrome(number num)
{
string n=num.value;
number reversenum, numsum, numsumreverse;
reversenum=num;
reversenum.reverse();
numsum.value=num.value;
numsumreverse.value=numsum.value;
numsumreverse.reverse();
ttmath::UInt<100> tempsum, numint, reversenumint;
int i=0;
while ((numsum.value.compare(numsumreverse.value) !=0) && i<200)
{
reversenum=num;
reversenum.reverse();
numint=num.value;
reversenumint=reversenum.value;
tempsum=numint+reversenumint;
numsum.value=String<ttmath::UInt<100> >(tempsum);
numsumreverse.value=numsum.value;
numsumreverse.reverse();
num.value=numsum.value;
i++;
}
if (i<200) cout << "The number " << n << " becomes palindromic after " << i << " steps : " << num.value << endl;
else
{
cout << "A solution for " << n << " could not be found!!!" << endl;
LychrelList=LychrelList+n+" ";
LychrelCount++;
}
}
int main()
{
cout << "From where to start?" << endl << ">";
int lbd,ubd;
cin >> lbd;
cout << endl << "And where to stop?" << endl <<">";
cin >> ubd;
cout << endl;
number temp;
int i;
for (i=lbd; i<=ubd; i++)
{
temp.value=to_string(i);
palindrome(temp);
}
if (LychrelList.compare("") !=0) cout << "The possible Lychrel numbers found in the range are:" << endl << LychrelList << endl << "Total - " << LychrelCount;
cout << endl << endl << "Press ENTER to end the program...";
cin.ignore(numeric_limits<streamsize>::max(), '\n');
string s;
getline(cin,s);
cout << "Thanks for using!";
return 0;
}
It's a really awesome community. Special thanks to Marco A. :)
UPDATE AGAIN: I've devised my own add() function that cuts the program's dependency on external libraries. It resulted in a smaller executable and faster performance too. Here is the code:
#include <iostream>
#include <string>
#include <algorithm>
#include <limits>
/* This program calculates the steps needed
to make a certain number palindromic.
It is designed to output the values for
numbers inside a desired range
*/
using namespace std;
string LychrelList;
int LychrelCount=0;
string add(string sA, string sB)
{
int iTemp=0;
string sAns;
int k=sA.length()-sB.length();
int i;
if (k>0){for (i=0;i<k;i++) {sB="0"+sB;}}
if (k<0) {for (i=0;i<-k;i++) {sA="0"+sA;}}
for (i=sA.length()-1;i>=0;i--)
{
iTemp+=sA[i]+sB[i]-96;
if (iTemp>9)
{
sAns=to_string(iTemp%10)+sAns;
iTemp/=10;
}
else
{
sAns=to_string(iTemp)+sAns;
iTemp=0;
}
}
if (iTemp>0) {sAns=to_string(iTemp)+sAns;}
return sAns;
}
void palindrome(string num)
{
string n=num;
string reversenum, numsum, numsumreverse;
numsum=num;
numsumreverse=numsum;
reverse(numsumreverse.begin(),numsumreverse.end());
int i=0;
while ((numsum.compare(numsumreverse) !=0) && i<200)
{
reversenum=num;
reverse(reversenum.begin(),reversenum.end());
numsum=add(num,reversenum);
numsumreverse=numsum;
reverse(numsumreverse.begin(),numsumreverse.end());
num=numsum;
i++;
}
if (i<200) cout << "The number " << n << " becomes palindromic after " << i << " steps : " << num << endl;
else
{
cout << "A solution for " << n << " could not be found!!!" << endl;
LychrelList=LychrelList+n+" ";
LychrelCount++;
}
}
int main()
{
cout << "From where to start?" << endl << ">";
int lbd,ubd;
cin >> lbd;
cout << endl << "And where to stop?" << endl <<">";
cin >> ubd;
cout << endl;
string temp;
int i;
for (i=lbd; i<=ubd; i++)
{
temp=to_string(i);
palindrome(temp);
}
if (LychrelList.compare("") !=0) cout << "The possible Lychrel numbers found in the range are:" << endl << LychrelList << endl << "Total - " << LychrelCount;
cout << endl << endl << "Press ENTER to end the program...";
cin.ignore(numeric_limits<streamsize>::max(), '\n');
string s;
getline(cin,s);
cout <<endl << "Thanks for using!";
return 0;
}
You guys here have helped me a lot to find my own way. Thanks everyone. :)
You're overflowing long long since the last two valid values of num.value and reversenum.value are 7197630720180367016 and 6107630810270367917 which, added together, are way above the maximum size of a long long (9223372036854775807 on my machine). That will yield a negative value and spoil your next call to stoll
std::out_of_range is thrown if the converted value would fall out of the range of the result type or if the underlying function (std::strtol or std::strtoll) sets errno to ERANGE.
(reference)
If you're trying to get the next smallest palindrome, you should use another approach like the one I explained here.
You can find a Live Example here
If you prefer to/must continue with your approach you should either do the addition manually on the strings or use a bigint library (again take a look at here and modify the plusOne() function to your liking)
From http://www.cplusplus.com/reference/string/stoll/
If the value read is out of the range of representable values by a long long, an out_of_range exception is thrown.
The ll data type cant handle the string length. My debugger tells me 196 breaks on the value
std::stoll (__str=\"9605805010994805921-\", __idx=0x0, __base=10)
The long long is too small.
You might want to do the addition on the strings themselves, without resorting to a numeric type.
I'm new to c++ and I'm trying to make a simple class roster program that accepts new students storing the student data in an array that then be sorted and display the contents of the array. However when running the program and entering the menu selection, two of the three functions do not work. Any help or guidance is much appreciated. My code is here.
#include <cstdio>
#include <cstdlib>
#include <iomanip>
#include <iostream>
using namespace std;
//Create Students class
class Students
{
public:
char sFirstName[256];
char sLastName[256];
int sStudentID;
double sGrade;
double sGPA;
double nCreditHours;
};
//functions
Students addStudent();
//void displayRoster();
//void sortRoster();
void showMenu();
void showWelcome();
//Welcome function
void showWelcome()
{
cout << "Welcome to my class roster program. \n"
<< "This program can be used to add students to the roster, \n"
<< "which can then be sorted by either name or I.D. number. \n"
<< endl;
}
//Menu function
void showMenu()
{
cout << " Student Roster: \n"
<< "MAIN MENU PLEASE SELECT AN OPTION" << endl;
cout << "1) Add student to roster: " << endl;
cout << "2) Display current roster: " << endl;
cout << "3) Sort roster: " << endl;
cout << "4) Exit program: " << endl;
//cout << "5) Display roster sorted by 'student I.D.': " << endl;
//cout << "6) Display roster sorted by 'Grade': " << endl;
//cout << "7) Display roster sorted by 'GPA': \n" << endl;
cout << " Make your selection: \n" << endl;
}
//Add student function
Students addStudent()
{
Students student;
cout << "Add student to roster. \n"
<< "Enter first name: " << endl;
cin >> student.sFirstName;
cout << "Enter last name: " << endl;
cin >> student.sLastName;
cout << "Enter student I.D.: " << endl;
cin >> student.sStudentID;
return student;
}
void displayStudent(Students student)
{
cout << "Student name: " << student.sFirstName << " "
<< student.sLastName << endl;
cout << "I.D. # " << student.sStudentID << endl;
}
void displayRoster()
{
Students student[256];
int nCount;
for (int index = 0; index < nCount; index++)
{
displayStudent(student[index]);
}
}
int getStudents(Students student[], int nMaxSize)
{
int index;
for (index = 0; index < nMaxSize; index++)
{
char uInput;
cout << "Enter another student to the roster? (Y/N): ";
cin >> uInput;
if (uInput != 'y' && uInput != 'Y')
{
break;
}
student[index] = addStudent();
}
return index;
}
void sortRoster()
{
Students student[256];
int nCount;
//bubble swap
int nSwaps = 1;
while (nSwaps != 0)
{
nSwaps = 0;
for (int n = 0; n < (nCount - 1); n++)
{
if (student[n].sStudentID > student[n+1].sStudentID)
{
Students temp = student[n+1];
student[n+1] = student[n];
student[n] = temp;
nSwaps++;
}
}
}
}
int main()
{
int selection; //menu selection variable
//constants for menu selection
const int ADD_STUDENT = 1,
DISPLAY_ROSTER = 2,
SORT_ROSTER = 3,
QUIT_PROGRAM = 4;
Students student[256];
//int nCount = getStudents(student, 256);
do
{
showWelcome(); //Show welcome message
showMenu(); //Show menu options
cin >> selection;
while (selection < ADD_STUDENT || selection > QUIT_PROGRAM)
{
cout << "Enter a valid selection: ";
cin >> selection;
}
if (selection != QUIT_PROGRAM)
{
switch (selection)
{
case ADD_STUDENT:
addStudent();
break;
case DISPLAY_ROSTER:
displayRoster();
break;
case SORT_ROSTER:
sortRoster();
break;
}
}
}
while (selection != QUIT_PROGRAM);
return 0;
}
The problem is not in the switch.
The addStudent() is not adding the student into any list or array. Also since it return type is Students you should add it into the any array of Students. Since you have not stored any data display won't display anything.
The another problem is of nCount. You are using it in for comparison without initializing it. Also to keep nCount synchronized either make it global, use as pointer or handle it with return.
Also the problem is in displayRoster(). You are declaring Students array as Students student[256]; and you are using it without initializing. Also if initialized, it won't have the data which was given as input.
NOTE: Sit and read your code again, there are many more mistakes. Try visualizing how your data should be stored and how your code is to behave and then start writing code.
Your nCount is not initialised. Since this variable is used in those two functions (and assuming that it refers to the total count), you can declare it as a global variable:
nCount=0;
Everytime you add a new entry, you can increment the counter as:
nCount++;
Another suggestion to make your code actually work:
student[i++]=addStudent();
where i is a counter initialised to 0. Your addStudent() function returns an object, and you discard it. Store it in the array of objects you created:
Students student[256];
Also, since you use the above in almost all functions, it is best to declare it as global rather than redeclaring in each function.
Apparently push_back() is not working for my custom data class T. On compilation I get the following error:
error: no matching function for call to ‘Vector::push_back(int&)’
Could someone explain to me why that is? Thank you.
#include <std_lib_facilities>
#include <numeric>
#include <vector>
#include <string>
// vector<int> userin;
// int total;
// bool success;
class T
{
public:
void computeSum(vector<T> userin, int sumamount, T& total, bool& success);
void getData(vector<T> userin);
};
template <class T>
void computeSum(vector<T> userin, int sumamount, T& total, bool& success)
{
if (sumamount < userin.size()){
success = true;
int i = 0;
while (i<sumamount){
total = total + userin[i];
++i;
}
} else {
success = false;
cerr << "You can not request to sum up more numbers than there are.\n";
}
}
template <class>
void getData(vector<T> userin)
{
cout << "Please insert the data:\n";
int n;
do{
cin >> n;
userin.push_back(n);
} while (n);
cout << "This vector has " << userin.size() << " numbers.\n";
}
int helper()
{
cout << "Do you want help? ";
string help;
cin >> help;
if (help == "n" || help == "no"){
return 0;
}else{
cout << "Enter your data. Negative numbers will be added as 0. Ctrl-D to finish inputing values.\n";
}
}
int main()
{
helper();
getData(userin);
cout << "How many numbers would you like to sum?";
int sumamount;
cin >> sumamount;
computeSum(userin, sumamount);
if (success = true) {
cout << "The sum is " << total << endl;
} else {
cerr << "Oops, an error has occured.\n";
}
cout << endl;
return 0;
}
Outside some flagrantly offensive issues (e.g. it should be template <class T>, not template<class>), the real problem is that vector expects you to push back objects of type T. It looks like you are reading in with type int and pushing. Try:
template <class>
void getData(vector<T> userin)
{
cout << "Please insert the data:\n";
T n;
do{
cin >> n;
userin.push_back(n);
} while (n);
cout << "This vector has " << userin.size() << " numbers.\n";
}
The problem is this line:
userin.push_back(n);
where n is an int. push_back is expecting something of type T.
I'm also not sure what the point of class T is in this case.