Write a program that simulates a lottery. The program should havean array of five integers named lottery, and shouldgenerate a r
andom number in the range of 0 through 9 for eachelement in the array. The user should enter five digits whichshould be stored in an integer array named user. Theprogram is to compare the corresponding elements in the two arraysand keep a count of the digits that match. For example, thefollowing shows the lottery array and the user array with samplenumbers stored in each. There are two matching digits (elements 2and 4).
lottery array: 7,4,9,1,3
user array: 4,2,9,7,3
The program should display the random numbers stored in the lotteryarray and the number of matching digits. If all the digits match,display a message proclaiming the user as a grand prize winner.
lottery array: 7,4,9,1,3
user array: 4,2,9,7,3
The program should display the random numbers stored in the lotteryarray and the number of matching digits. If all the digits match,display a message proclaiming the user as a grand prize winner.
1 answer:
Answer:
Here is the C++ program that simulates lottery:
#include<iostream> //to use input output functions
using namespace std; //to access objects cin cout
int main(){ //start of main function
int size= 5; // size of arrays
int range = 10; //range of random numbers from 0 to 9
int user[size]; // user array
int lottery[size]; // lottery array
for(int i=0;i<size;i++) //iterates through the array
lottery[i]=rand()%range; // generates random number in specified range
cout<<"Enter "<<size<<" digits: "; //prompts user to enter 5 digits
for(int i=0;i<size;i++) //loops through the user array
cin>>user[i]; //reads input digits from user
int match=0; //stores number of matching digits
for(int i=0;i<size;i++) //iterates through array to compare user and lottery arrays
if(user[i]==lottery[i]) //if digit at i-th index of user array matches to that of lottery array
match++; //increments count of matching digits by 1
cout<<"Lottery array: "; // display digits of lottery array
for(int i=0;i<size;i++) //iterates through elements of lottery array
cout<<lottery[i]<<" "; //prints elements of lottery array with a space between them
cout<<endl; //prints a new line
cout<<" User array: "; // prints digits of user array
for(int i=0;i<size;i++) //iterates through elements of user array
cout<<user[i]<<" "; //prints elements of user array
cout<<endl; // prints a new line
if(match==size){ //if all the digits match
cout<<"Congratulations. You are a grand prize winner! "; }//displays this message proclaiming the user as a grand prize winner
else{ // if all digits of user array do not match with lottery array digits
cout<<"Number of digits matched: "<<match<<endl; //displays the number of matched digits
cout<<"Sorry! Better luck next time!" ; //displays this message when all digits don't match
}
}
Explanation:
If you want to keep the size and range fixed then you can use #define before the main() function to give a constant value to size and range as:
#define size 5
#define range 10
The program uses rand() function in order to generate random numbers for lottery array in the range of 0 through 9.
Then the program declares a user array with size = 5 and prompts user to enter 5 digits to stores in user array.
Next the program matches each digit of user array to the corresponding digit of lottery array and if the two digits match then the program increments the match variable by 1 to count the matched digits. For example, lets say lottery has the following elements:
lottery: 7,4,9,1,3
Lets say user array has following elements input by user at console
user: 4,2,9,7,3
Now at first iteration the digit 7 at 0-th index of lottery array is matched to the digit 4 at 0-th index of user array. This index is specified using variable i. These means the first element of lottery array is matched with first element of user array. As these digits are not equal so they don't match and the variable i is incremented to point to the position of next digit.
Now at second iteration the digit 4 in lottery array is matched to the digit 2 of user array. As these digits are not equal so they don't match and the variable i is incremented.
at third iteration the digit 9 in lottery array is matched to the digit 9 of user array. As these digits equal so they match and the variable match is incremented to 1 in order to count the number of matches. So value of match = 1
Now at fourth iteration the digit 1 in lottery array is matched to the digit 7 of user array. As these digits are not equal so they don't match and the variable i is incremented. The value of match also remains the same i.e. 1
at fifth iteration the digit 3 in lottery array is matched to the digit 3 of user array. As these digits equal so they match and the variable match is incremented to 1 in order to count the number of matches. So value of match = 2
Next the loop ends because the value of exceeds 5 which is the size of the array.
Next if(match==size) statement has an if condition which checks if all digits match. This is checked by comparing the count of match variable to the size of the array. The value of match is 2 and value of size is 5 so this means that all the digits do not match. Hence this condition evaluates to false. So the statement in if part will not execute and program moves to the statement: cout<<"Number of digits matched: "<<match<<endl; which displays the value of match variable i.e. 2 as:
Number of digits matched: 2
followed by statement cout<<"Sorry! Better luck next time!" ; which displays the message:
Sorry! Better luck next time!
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Answer:
Here is the program that determines the number of questions that the student answered correctly.
#include <iostream> //to use input output functions
#include <fstream> // to handle files
#define size 20 //size of questions is fixed to 20
using namespace std; //to identify objects cin cout
int correctAnswers(char answers[], char correct[]); //to count correct answers given by student
int main(){ //start of main function
char correct[size]; // array stores correct answers
char answers[size]; //stores answers of students
int result; //stores the correct answers result of student
double percentage; //stores the percentage of correct answers
int counter; //counts number of correct answers given by student
ifstream reader("CorrectAnswers.txt"); //reads the contents of CorrectAnswers.txt file
if(!reader){ //if file cannot be read/opened
cout<<"Cannot open the file"<<endl; //displays error message
return 0; }
counter = 0; //sets counter to 0 initially
while( (reader>>correct[counter++]) && counter < size ); //reads each answer from CorrectAnswers.txt and stores it in char array correct[] at each iteration of while loop
reader.close(); //closes the file
reader.open("StudentAnswers.txt"); //opens StudentAnswers.txt file
if(!reader){ //if file could not be opened
cout<<"Cannot open file"<<endl; //displays this error message
return 0; }
counter = 0; //sets counter to 0
while( (reader>>answers[counter++]) && counter < size ); //reads each answer from StudentAnswers.txt and stores it in char array answers[] at each iteration of while loop
result = correctAnswers(answers,correct); //calls correctAnswers method to compute the correct answers given by student and stores the result of correct answers in result variable
percentage = 100.0*result/size; //computes percentage of correct answers of student
cout<<"The total number of questions answered correctly: "<<result<<endl; //displays total no of qs answered correctly
cout<<"The percentage of questions answered correctly: "<<percentage<<" %"<<endl; //displays computed percentage
if( percentage >= 75 ){ //if percentage of correctly answered questions is 75% or greater
cout<<"Student has passed the exam!"<<endl; } //displays that the student passed the exam
else { //if percentage of correctly answered questions is below 75%
cout<<"Student has failed the exam!"<<endl; } //displays that the student failed the exam
return 0; }
int correctAnswers(char answers[], char correct[]){ //method to compute the number of correct answers
int countCorrect = 0; //stores the count of correct answers
for(int i=0; i<size; i++){ //iterates 20 times to match answers from both the files of 20 questions
if( answers[i] == correct[i] ){ // if the student answer in StudentAnswers.txt file matches with the correct answer given in CorrectAnswers.txt file
countCorrect++; } } //adds 1 to the countCorrect every time the student answer matches with the correct answer
return countCorrect; } //returns the number of questions that the student answered correctly
Explanation:
The program is well explained in the comments mentioned with each line of code.
Here are the two files that can be used to check the working of the above program. You can create your own text files too.
CorrectAnswers.txt :
A
A
B
D
C
C
A
C
D
D
A
B
A
B
B
C
A
C
C
B
StudentAnswers.txt
A
C
B
D
C
C
B
C
D
C
D
B
A
B
B
C
A
C
C
B
Also if the number of wrong answers are to be displayed then add this method to the above code:
void wrongAnswers(char answers[], char correct[]){ //method takes two arrays one with correct answers and the other with student answers
for(int i=0; i<size; i++){ //iterates 20 times
if( answers[i] != correct[i] ){ //if the answer by student does not match with correct answer
cout<<"Question Number: "<<i+1<<endl; //the question that is answered incorrectly
cout<<"Correct answer is: "<<correct[i]<<endl; //displays the correct answer
cout<<"Student answer is: "<<answers[i]<<endl; } } } //displays the answer that student gave
Now call this method in main() as:
if(result < size){ //if result is less than size i.e. 20
cout<<"The questions answered incorrectly"<<endl; //number of questions that are answered incorrectly
wrongAnswers(answers,correct); //calls method to compute the wrongly answered questions
}else{ //if result is not less than size
cout<<"No incorrect answers."<<endl; } //no questions incorrectly answered
cout<<"Number of missed questions: "<<size-result<<endl; //displays the number of missed questions
The screenshot of the output is attached.
