I'm a novice in C++ so don't really know much but I want to learn and practice. I've written a code where the user will state how many persons he/she wants to write the names, and the names will be in char. I will then have to sort this using insertion to see which name is well sorted Alphabetically.
#include <iostream>
using namespace std;
class Name{
public:
void sortInsertion(int, char* );
};
void Name::sortInsertion(int size, char *c){
for (int i = 1; i < size - 1; i++){
int j;
j = i;
while (j > 0 && c[j] < c[j - 1]){
swap(c[j], c[j - 1]);
j = j - 1;
}
}
}
int main(){
Name n;
char* name;
name = new char[30];
int* in;
int size = 0;
in = new int[size];
cout << "How many people?: ";
cin >> size;
for (int i = 0; i < size; i++){
cout << "Person " << i+1 <<": "<< endl;
cout << "Full Name: ";
cin.ignore();
cin.getline(name,29);
cout << endl;
}
n.sortInsertion(size, name);
for (int i = 0; i < size; i++){
cout << "Person " << i + 1 << ": " << endl;
cout << "Full Name: ";
cout << name << endl;
}
system("pause");
}
this is my code. It doesn't show the result as I want it to show, the output misses the first letter of the name and only repeats the printing of the last user input given.
Could you please tell me what's wrong? Any help and tip is really appreciated :)
Related
I need to create a program that asks the user for N unique values and print the values in descending order for every number entered. The problem is it only outputs the number 0. Can anyone point out what is wrong with my code?
#include <iostream>
using namespace std;
int main(){
//declare the variables
int N, j, i, k, z, desc, temp, sorter[N];
bool found;
//Ask the user for N size array
cout << "Enter array size: ";
cin >> N;
while(N<5){
cout << "Invalid value. N must be greater than five(5)" << endl;
cout << "Enter array size: ";
cin >> N;
}
int list[N];
//Printing how many values they need to enter
cout << " " << endl;
cout << "Please enter " << N << " values" << endl;
//Code of the program
for (int i = 0; i < N; i++){
do{
found = false;
cout << "\n" << endl;
cout << "Enter value for index " << i << ": ";
cin >> temp;
for (int j = 0; j < i; j++)
if (list[j] == temp)
found = true;
if (found == true)
cout << "Value already exist";
else{
for(int k = 0; k < i; k++){
int key = sorter[k];
j = k - 1;
while(j >= 0 && key >= sorter[j]){
sorter[j + 1] = sorter[j];
j--;
}
sorter[j + 1] = key;
}
cout << "\nValues: ";
for(int z = 0; z <= i; z++){
cout << sorter[z] <<" ";
}
}
} while(found == true);
sorter[i] = temp;
}
You shouldn't be defining the array 'sorter[N]', the position, where you are currently, because you don't have the value of 'N', during compilation the arbitrary amount of space will be allocated to the the array.
solve the other compiling errors in your code.
What you want is just a 3-line code:
#include <algorithm>
#include <iostream>
#include <iterator>
#include <vector>
int main() {
std::vector<int> vecOfNumbers = { 1,3,5,7,9,8,6,4,2 }; // scan these numbers if you want
std::sort(vecOfNumbers.begin(), vecOfNumbers.end());
std::copy(vecOfNumbers.rbegin(), vecOfNumbers.rend(), std::ostream_iterator<int>(std::cout, " "));
return 0;
}
Make sure you understand it before using it
I finished this code homework assignment tonight. I thought I was done, but I just realized that my "Average" value is coming out wrong with certain values. For example: When my professor entered the values 22, 66, 45.1, and 88 he got an "Average" of 55.27. However, when I enter those values in my program, I get an "Average" of 55.25. I have no idea what I am doing wrong. I was pretty confident in my program until I noticed that flaw. My program is due at midnight, so I am clueless on how to fix it. Any tips will be greatly appreciated!
Code Prompt: "Write a program that dynamically allocates an array large enough to hold a user-defined number of test scores. Once all the scores are entered, the array should be passed to a function that sorts them in ascending order. Another function should be called that calculates the average score. The program should display the sorted list of scores and averages with appropriate headings. Use pointer notation rather than array notation whenever possible."
Professor Notes: The book only states, "Input Validation: Do not accept negative numbers for test scores." We also need to have input validation for the number of scores. If it is negative, including 0, the program halts, we should consider this situation for 'counter' not to be negative while we have a loop to enter numbers. So negative numbers should be rejected for the number of scores and the values of scores.
Here is my code:
#include <iostream>
#include <iomanip>
using namespace std;
void showArray(double* array, int size);
double averageArray(double* array, int size);
void orderArray(double* array, int size);
int main()
{
double* scores = nullptr;
int counter;
double numberOfScores;
cout << "\nHow many test scores will you enter? ";
cin >> numberOfScores;
if (numberOfScores < 0) {
cout << "The number cannot be negative.\n"
<< "Enter another number: ";
cin >> numberOfScores;
}
if (numberOfScores == 0) {
cout << "You must enter a number greater than zero.\n"
<< "Enter another number: ";
cin >> numberOfScores;
}
scores = new double[numberOfScores];
for (counter = 0; counter < numberOfScores; counter++) {
cout << "Enter test score " << (counter + 1) << ": ";
cin >> *(scores + counter);
if (*(scores + counter) < 0) {
cout << "Negative scores are not allowed. " << endl
<< "Enter another score for this test : ";
cin >> *(scores + counter);
}
}
orderArray(scores, counter);
cout << "\nThe test scores in ascending order, and their average, are: " << endl
<< endl;
cout << " Score" << endl;
cout << " -----" << endl
<< endl;
showArray(scores, counter);
cout << "\nAverage Score: "
<< " " << averageArray(scores, counter) << endl
<< endl;
cout << "Press any key to continue...";
delete[] scores;
scores = nullptr;
system("pause>0");
}
void orderArray(double* array, int size)
{
int counterx;
int minIndex;
int minValue;
for (counterx = 0; counterx < (size - 1); counterx++) {
minIndex = counterx;
minValue = *(array + counterx);
for (int index = counterx + 1; index < size; index++) {
if (*(array + index) < minValue) {
minValue = *(array + index);
minIndex = index;
}
}
*(array + minIndex) = *(array + counterx);
*(array + counterx) = minValue;
}
}
double averageArray(double* array, int size)
{
int x;
double total{};
for (x = 0; x < size; x++) {
total += *(array + x);
}
double average = total / size;
return average;
}
void showArray(double* array, int size)
{
for (int i = 0; i < size; i++) {
cout << " " << *(array + i) << endl;
}
}
I try to start my answers with a brief code review:
#include <iostream>
#include <iomanip>
using namespace std; // Bad practice; avoid
void showArray(double* array, int size);
double averageArray(double* array, int size);
void orderArray(double* array, int size);
int main()
{
double* scores = nullptr;
int counter;
double numberOfScores;
cout << "\nHow many test scores will you enter? ";
cin >> numberOfScores;
// This is not input validation, I can enter two consecutive bad values,
// and the second one will be accepted.
if (numberOfScores < 0) {
// Weird formatting, this blank line
cout << "The number cannot be negative.\n"
<< "Enter another number: ";
cin >> numberOfScores;
}
// The homework, as presented, doesn't say you have to treat 0 differently.
if (numberOfScores == 0) {
cout << "You must enter a number greater than zero.\n"
<< "Enter another number: ";
cin >> numberOfScores;
}
scores = new double[numberOfScores];
// Declare your loop counter in the loop
for (counter = 0; counter < numberOfScores; counter++) {
cout << "Enter test score " << (counter + 1) << ": ";
cin >> *(scores + counter);
if (*(scores + counter) < 0) {
cout << "Negative scores are not allowed. " << endl
<< "Enter another score for this test : ";
cin >> *(scores + counter);
}
}
orderArray(scores, counter); // Why not use numberOfScores?
cout << "\nThe test scores in ascending order, and their average, are: " << endl
<< endl;
cout << " Score" << endl;
cout << " -----" << endl
<< endl;
showArray(scores, counter); // Same as above.
cout << "\nAverage Score: "
<< " " << averageArray(scores, counter) << endl
<< endl;
cout << "Press any key to continue...";
delete[] scores;
scores = nullptr;
system("pause>0"); // Meh, I suppose if you're on VS
}
void orderArray(double* array, int size)
{
int counterx;
int minIndex;
int minValue; // Unnecessary, and also the culprit
// This looks like selection sort
for (counterx = 0; counterx < (size - 1); counterx++) {
minIndex = counterx;
minValue = *(array + counterx);
for (int index = counterx + 1; index < size; index++) {
if (*(array + index) < minValue) {
minValue = *(array + index);
minIndex = index;
}
}
*(array + minIndex) = *(array + counterx);
*(array + counterx) = minValue;
}
}
double averageArray(double* array, int size)
{
int x;
double total{};
for (x = 0; x < size; x++) {
total += *(array + x);
}
double average = total / size;
return average;
}
void showArray(double* array, int size)
{
for (int i = 0; i < size; i++) {
cout << " " << *(array + i) << endl;
}
}
When you are sorting your array, you keep track of the minValue as an int and not a double. That's why your average of the sample input is incorrect. 45.1 is truncated to 45 for your calculations. You don't need to keep track of the minValue at all. Knowing where the minimum is, and where it needs to go is sufficient.
But as I pointed out, there are some other serious problems with your code, namely, your [lack of] input validation. Currently, if I enter two consecutive bad numbers, the second one will be accepted no matter what. You need a loop that will not exit until a good value is entered. It appears that you are allowed to assume that it's always a number at least, and not frisbee or any other non-numeric value.
Below is an example of what your program could look like if your professor decides to teach you C++. It requires that you compile to the C++17 standard. I don't know what compiler you're using, but it appears to be Visual Studio Community. I'm not very familiar with that IDE, but I imagine it's easy enough to set in the project settings.
#include <algorithm>
#include <iomanip>
#include <iostream>
#include <numeric>
#include <string>
#include <vector>
// Assumes a number is always entered
double positive_value_prompt(const std::string& prompt) {
double num;
std::cout << prompt;
do {
std::cin >> num;
if (num <= 0) {
std::cerr << "Value must be positive.\n";
}
} while (num <= 0);
return num;
}
int main() {
// Declare variables when you need them.
double numberOfScores =
positive_value_prompt("How many test scores will you enter? ");
std::vector<double> scores;
for (int counter = 0; counter < numberOfScores; counter++) {
scores.push_back(positive_value_prompt("Enter test score: "));
}
std::sort(scores.begin(), scores.end());
for (const auto& i : scores) {
std::cout << i << ' ';
}
std::cout << '\n';
std::cout << "\nAverage Score: "
<< std::reduce(
scores.begin(), scores.end(), 0.0,
[size = scores.size()](auto mean, const auto& val) mutable {
return mean += val / size;
})
<< '\n';
}
And here's an example of selection sort where you don't have to worry about the minimum value. It requires that you compile to C++20. You can see the code running here.
#include <iostream>
#include <random>
#include <vector>
void selection_sort(std::vector<int>& vec) {
for (int i = 0; i < std::ssize(vec); ++i) {
int minIdx = i;
for (int j = i + 1; j < std::ssize(vec); ++j) {
if (vec[j] < vec[minIdx]) {
minIdx = j;
}
}
int tmp = vec[i];
vec[i] = vec[minIdx];
vec[minIdx] = tmp;
}
}
void print(const std::vector<int>& v) {
for (const auto& i : v) {
std::cout << i << ' ';
}
std::cout << '\n';
}
int main() {
std::mt19937 prng(std::random_device{}());
std::uniform_int_distribution<int> dist(1, 1000);
std::vector<int> v;
for (int i = 0; i < 10; ++i) {
v.push_back(dist(prng));
}
print(v);
selection_sort(v);
print(v);
}
I opted not to give your code the 'light touch' treatment because than I would have done your homework for you, and that's just not something I do. However, the logic shown should still be able to guide you toward a working solution.
I need to add a function to search in the string array and bring up the user with associated phone number. Though Im lost. Any functions created only bring up the persons name without the number. If not found, it needs to say error.
int main(int argc, char** argv)
{
int i, n, j;
string name[100];
string phone[100];
int index[100];
cout << "How many names and phone numbers do you want to enter? " << endl
<< "Entering 0 ends the program." << endl;
cin >> n;
if (n == 0)
return 0;
for (i = 0; i < n; i++) {
cout << "Please enter a name: ";
cin >> name[i];
cout << "Please enter a phone number: ";
cin >> phone[i];
}
for (i = 0; i < n; i++) {
index[i] = i;
}
for (i = 0; i < n; i++) {
for (j = i + 1; j < n; j++) {
int temp;
if (phone[index[i]] > phone[index[j]]) {
temp = index[i];
index[i] = index[j];
index[j] = temp;
}
}
}
cout << "These entries are in ascending order by phone number: " << endl;
cout << "Name"
<< " "
<< "Phone Number" << endl;
for (i = 0; i < n; i++) {
cout << name[index[i]] << " " << phone[index[i]] << endl;
}
return 0;
}
This code should work for you (if i understood the question)
int search(string name[], string searchedName){
for(int i=0; i<100; i++){
if(searchedName == name[i])
return i; //Returns the position of the person, which is also the index of his phone number
}
return -1; //If -1 is returned it means there is no such name an "searchedName" in the vector
}
You can call this function like this
int main(){
/* all the stuff you already have inside here */
string nameToSearch;
cout<<"Insert the name of the person you want to see the number of"<<endl;
cin>>nameToSearch;
int position = search(name, nameToSearch);
if(position == -1)
cout<<"Sorry, "<<nameToSearch<<" is not in our list"<<endl;
else
cout<<"The phone number of "<<nameToSearch<<" is "<<phone[position]<<endl;
return 0;
}
Of course this is pretty basic and you can make it better, hope it helps!
I wrote a program to accept 15 integer values in an array, then pass this array to a function which will multiply each even index value by 4.
Currently the program displays the initial array, but seems like it's getting hung up before it displays the modified array.
Please help me understand why the program is getting stuck here!
int main(){
const int SIZE = 15;
int quad[SIZE] = {};
void quadruple(int[], const int);
cout << "Enter 15 integer values into an array." << endl;
for (int i = 0; i < SIZE; i++) // Accept 15 int values
{
cout << i << ": ";
cin >> quad[i];
}
cout << "Before quadruple function is called: " << endl;
for (int i = 0; i < SIZE; i++)
{
cout << quad[i] << " ";
}
cout << endl;
quadruple(quad, SIZE);
cout << "After even index value multiplication: " << endl;
for (int i = 0; i < SIZE; i++)
{
cout << quad[i] << " ";
}
cout << endl;
return 0;
}
void quadruple(int values[], const int SZ){
for (int i = 0; i < SZ; i + 2) // Multiply even values by 4
{
if ((i % 2) == 0)
{
values[i] = values[i] * 4;
}
else // Keep odd values the same
{
values[i] = values[i] * 1;
}
}
}
for (int i = 0; i < SZ; i + 2)
"i + 2" doesn't do anything.
You probably meant "i += 2;".
Your homework assignment is to find some documentation about your system's debugger. And find where your rubber duck is, as it's been suggested in the comments.
So I'm trying to create an array that contains some user inputted names, and then associate those names with letter grades from tests (ex: A, B, C, D, F). My question is, how would I use an array to accept the user inputted names?
EDIT:
Sorry this is a bit long, I don't know what part to put that would help out. Totally new to C++ and I can't seem to find anything online regarding the matter, lol.
Here is some code. This program currently asks the user for test scores, then displays and drops the lowest test score, and finally, calculates the average of the scores without the lowest one. The end goal is to ask the user for 5 students names, and 4 scores for each student, then dropping the lowest score for each student and calculating the averages of ALL scores inputted regardless of student.
#include <iostream>
#include <string>
using namespace std;
void getScore(int &);
int findLowest(int [], int);
void calcAverage(int [], int);
int main () {
const int NUM_SCORES = 5;
int scores[NUM_SCORES];
cout << "Welcome to test averages." << endl;
cout << "Please enter scores for " << NUM_SCORES << " students." << endl;
cout << endl;
for (int i = 0; i < NUM_SCORES; i++) {
getScore(scores[i]);
}
for (int i = 0; i < NUM_SCORES; i++) {
cout << "Score " << (i + 1) << ": " << scores[i] << endl;
}
cout << endl;
cout << "The lowest of these scores is " << findLowest(scores, NUM_SCORES) << endl;
calcAverage(scores, NUM_SCORES);
return 0;
}
void getScore(int & s) {
s = -1;
cout << "Please enter a test score: ";
cin >> s;
while (s < 0 || s > 100) {
cout << "Score range must be from 0-100" << endl;
cout << "Please re-enter a score: ";
cin >> s;
}
}
int findLowest(int theArray [], int theArraySize) {
int lowest = theArray[0];
for (int i = 1; i < theArraySize; i++) {
if (theArray[i] < lowest) {
lowest = theArray[i];
}
}
return lowest;
}
void calcAverage(int theArray [], int theArraySize) {
int sum = 0;
for (int i = 0; i < theArraySize; i++) {
sum += theArray[i];
}
double average = (sum - findLowest(theArray, theArraySize)) / (theArraySize - 1.0);
cout << "The average is " << average << endl;
}
Try getline from #include <string>
std::string names[5];
for (int i = 0; i < 5; ++i){
getline(std::cin, names[i]);
}