So I'm Having A Recursion Bug.
OutPut I Want...
Input 4
* * * *
* * *
* *
*
* *
* * *
* * * *
OutPut I Get..
Input 4
* Big Blank Space*
I Cant Seem To Wrap My Head Very Well Around recursion.
#include<iostream>
#include<fstream>
#include<string>
#include<windows.h>
#include<ctime>
using namespace std;
int i;
bool end = false;
int changer = -1;
int placeHolder;
bool recursionUp(int num1)
{
if(num1 == placeHolder)
{
return true;
}
for(i = placeHolder; i == num1; i--)
{
cout << "*";
}
cout << "\n";
recursionUp(num1 + 1);
}
bool cont = false;
int recursion(int num1)
{
if(num1 == 0)
{
cont = recursionUp(num1);
}
for(i = 1; i <= num1; i++)
{
cout << "*";
}
recursion(num1 - 1);
if(cont)
{
return 0;
}
}
int main()
{
int number;
cout << "Input Star Number...\n";
cout << "\t Input: ";
cin >> number;
placeHolder = number;
recursion(number);
return 0;
}
Can someone point out my mistake?
As with any recursion there are two things you'll need to define:
The end condition
A depth value (and any other information that's needed)
In your case the end condition is when depth == number - 1
You'll want to print before and after each recursion.
void recursion(int depth){
if (depth <= 1) {
cout << '*' << endl << endl;
}else{
for (int i = 0; i < depth; ++i)cout << "* ";
cout << endl << endl;
recursion(depth - 1);
for (int i = 0; i < depth; ++i)cout <<"* ";
cout << endl << endl;
}
}
Related
I have something which outputs all the factors for an integer using a fixed loop.
in this case, int_end_int_ = 4
and middle_x_coefficient = 4
for (int i = 1; i <= int_end_int_; i++)
{
if (int_end_int_ % i == 0) // This gets the factors
{
//here
}
}
i have that inside the if loop that if i * 2 == 4, print a string. So i thought that when i = 2, it will output the string.
//inside if loop
int newi = i * 2;
//i = 2
if (newi == middle_x_coefficient) {
preroot1 = i; //ignore
cout << "prerooted";
preroot2 = i; //ignore
}
It does not output "prerooted", and i have no clue why.
Full Code:
#include <iostream>
#include <string>
using namespace std;
int main()
{
cout << "Quadratic Equation Solver ( to roots )" << endl;
cout << "Enter quadratic equation, e.x (x^2 + 4x + 4) must be in this form" << endl;
string equation;
cout << ">> ";
getline(cin, equation);
if (equation.length() < 12)
{
cout << "Please enter valid string." << endl;
while (equation.length() < 12)
{
cout << ">> ";
getline(cin, equation);
}
}
char middle_x_coefficient = equation[6]; // getting x^2 + 4(this<-)x + 4
char end_int_ = equation[11]; // getting x^2 + 4x + 4 <-- this
int preroot1 = 0;
int preroot2 = 0;
int int_end_int_ = static_cast<int>(end_int_); //convert char to int using static cast for like no reason
//nvm <- https://stackoverflow.com/questions/103512/why-use-static-castintx-instead-of-intx this says it is better bc compiler bad or smthn
int_end_int_ -= 48; //This converts the ascii value (52 for 4) to 4 (-48)
int pasti = 0;
for (int i = 1; i <= int_end_int_; i++)
{
if (int_end_int_ % i == 0)
{
cout << i << "this<- i" << endl;
cout << middle_x_coefficient << "this<- x" << endl;
int newi = i * 2;
//i = 2
if (newi == middle_x_coefficient) {
preroot1 = i;
cout << "prerooted";
preroot2 = i;
}
else if (i + pasti == middle_x_coefficient) {
preroot1 = i;
preroot2 = pasti;
}
pasti = i;
}
}
cout << preroot1 << " " << preroot2 << endl;
return 0;
}
You converted the character end_int_ to the integer int_end_int_, but you didn't convert the character middle_x_coefficient to an integer. Convert and use converted integer just as you did for end_int_.
Instead of using magic number 48, using character literal '0' is better.
in my project there are 2 structures, one of which relates to a binary tree, the second to students data
in ' int main ' I can’t access the add function GETDATA
' 'ZKR' does not refer to a value . ' (xcode)
I also can’t create a counter of the number of vertices of my tree
#include <iostream>
#include <ctime>
#include <cstring>
using namespace std;
struct ZKR {
char FACULTY[30];
int ACADEMIC_DEGREE;
char FIO[30];
};
struct point
{
char *data;
point *left;
point *right;
};
point* tree(int n, point* p)
{
point *r;
int nl, nr;
if (n == 0) { p = NULL; return p; }
nl = n / 2;
nr = n - nl - 1;
r = new point;
char s[50];
cout << "Значение: ";
cin >> s;
r->data = new char[strlen(s) + 1];
strcpy(r->data,s);
r->left = tree(nl, r->left);
r->right = tree(nr, r->right);
p = r;
return p;
}
void GETDATA(ZKR*M, int N)
{
cin.ignore();
for (int i = 0; i < N; i++)
{
cout << "\n";
cout << "FACULTY: ";
cin.getline(M[i].FACULTY, 30);
cout << "\n";
cout << "FIO: ";
cin.getline(M[i].FIO, 30);
cout << "\n";
cout << "ACADEMIC DEGREE: ";
cin >> M[i].ACADEMIC_DEGREE;
cin.ignore();
}
}
void treeprint(point *p, int &count) {
if (p != NULL) {
treeprint(p->left, count);
cout << p->data << " ";
treeprint(p->right, count);
if ((p->left == NULL) && (p->right == NULL))
count = count + 1;
}
}
int main()
{
setlocale(LC_ALL, "russian");
srand(time(NULL));
int n = 0, k = 0, count = 0;
point *beg = nullptr;
cout << "Enter the number of students" << endl;
int N;
cin >> N;
ZKR*M = new ZKR[N];
do
{
cout << "1. BUILD a binary tree\n";
cout << "2. SHOW a binary tree\n";
cout << "3. GETDATA\n";
cin >> k;
switch (k)
{
case 1:
cout << "Введите количество элементов" << endl;
cin >> n;
beg = tree(n, beg);
cout << endl;
break;
case 2:
treeprint(beg, count);
cout << endl;
cout << "Листьев в дереве: " << count << endl;
break;
case 3:
GETDATA(ZKR*M, N);
break;
}
} while (k != 4);
system("pause");
return 0;
}
I will be grateful for any help
This line is not syntactically correct:
GETDATA(ZKR*M, N);
Replace it with:
GETDATA(M, N);
M is a pointer to an object of type ZKR.
I am using C++ and want to do a 2-dimensional array. 10 rows and 3 columns. First column is(1 through 10). For Second column, user enters his/her choice of a number from (1-10) resulting in a times table displaying the results as follows: In this example the user's choice is '4':
1x4=4
2x4=8
3x4=12
4x4=16
5x4=20
6x4=24
7x4=28
8x4=32
9x4=36
10x4=40
I can't get the user's input to calculate correctly when using the for loop.
Well you can try this to get that output
#include<iostream>
using namespace std;
int main()
{
int n; //To take input
int table[10][3]; // Table
cout << "Input a number: ";
cin >> n;
// Generating Output
for (int i = 0; i < 10; i++)
{
table[i][0] = i + 1;
table[i][1] = n;
table[i][2] = table[i][0] * table[i][1];
}
for (int i = 0; i < 10; i++)
{
cout << table[i][0] << " * " << table[i][1] << " = " << table[i][2]<<endl;
}
return 0;
}
Output
SOLVED: Everything seems to be working now!! Here's the code:
#include <iostream>
#include<cstdlib>
#include<iomanip>
#include <ctime>
using namespace std;
void displayTable(int table[10][3]);
bool testMe(int testTable[10][3]);
void createTables(int testTable[10][3], int ansTable[10][3], int
usersChoice);
bool AllAnswersAreTested(bool tested[10]);
void gradeMe(int testTable[10][3], int ansTable[10][3]);
void displayMenu();
int main()
{
srand(time(NULL));
int userInput = 0;
int tableChoice = 0;
int myTable[10][3] = {0};
int testTable[10][3];
int ansTable[10][3];
bool tested = false;
do
{
displayMenu(); //Display the menu of choices
cin >> userInput;
cout << endl;
switch (userInput) //Validate menu choices 1-4
{
case 1: //Display a users choice of table
displayTable(myTable);
break;
case 2: //Test user on users choice of table
cout << "What times table test would you like to take? > ";
cin >> tableChoice;
createTables(testTable, ansTable, tableChoice);
tested = testMe(testTable);
if (tested)
{
gradeMe(testTable, ansTable);
}
break;
case 3: //Display a new table of the users choice
displayTable(myTable);
break;
case 4: //Quit program menu option
cout << "Program ending.\n";
return 0;
default: //Invalid entry
cout << "You entered an invalid item number. Please enter a number from 1 to 4.\n";
cout << endl;
}
} while (userInput != 4);
return 0;
}
void displayTable(int myTable[10][3])
{
int num; //initialize local variables
//Ask the user what times table they would like to review
cout << "What times table would you like to review?" << endl;;
cout << "Please enter a value from 1 to 12 > \n";
cout << "\n";
cin >> num;
cout << endl;
for (int i = 0; i < 10; i++)
{
myTable[i][0] = i + 1;
myTable[i][1] = num;
myTable[i][2] = myTable[i][0] * myTable[i][1];
}
for (int i = 0; i < 10; i++)
{
cout << setw(3)<< myTable[i][0] << " * " << myTable[i][1] << " = " << myTable[i][2] << endl;
}
cout << endl;
}
void createTables(int testTable[10][3], int ansTable[10][3], int usersChoice)
{
for (int i = 0; i < 10; i++)
{
testTable[i][0] = i + 1;
testTable[i][1] = usersChoice;
testTable[i][2] = 0;
ansTable[i][0] = i + 1;
ansTable[i][1] = usersChoice;
ansTable[i][2] = usersChoice * (i + 1);
}
}
bool testMe(int testTable[10][3])
{
bool tested[10] = { false, false, false, false, false,false, false, false, false, false };
while (!AllAnswersAreTested(tested))
{
int index = rand() % 10;
if (tested[index] == false)
{
int randomNum = testTable[index][0];
int tableChoice = testTable[index][1];
int answer;
cout << "What is " << randomNum << " X " << tableChoice << " = ";
cin >> answer;
testTable[index][2] = answer;
tested[index] = true;
}
}
return true;
}
bool AllAnswersAreTested(bool tested[10])
{
for (int i = 0; i < 10; i++)
{
if (tested[i] == false)
{
return false;
}
}
return true;
}
void gradeMe(int testTable[10][3], int ansTable[10][3])
{
int correctAnswers = 0;
for (int i = 0; i<10; i++)
{
if (testTable[i][2] == ansTable[i][2])
{
correctAnswers++;
}
}
int score = (correctAnswers * 10);
if (score == 100)
{
cout << "You passed the test! PERFECT SCORE!!" << endl;
cout << endl;
}
else if (score >= 70)
{
cout << "You passed the test. Your Score is: ";
cout << score;
cout << endl;
}
else if (score < 70)
{
cout << "You did not pass the test. Your Score is: ";
cout << score;
cout << endl;
}
}
//Display the menu function
void displayMenu()
{
cout << " Multiplication Tables" << endl;
cout << endl;
cout << " 1. Review MyTable" << endl;
cout << " 2. Test Me" << endl;
cout << " 3. Enter a New Multiplication Table (1-12)";
cout << " 4. Quit" << endl;
cout << " Enter a Menu Item > ";
}
#include <iostream>
using namespace std;
int main()
{
int a[100][100];
for(int i=1;i<10;i++){
for(int j=1;j<10;j++){
a[i][j] = (i)*(j);
cout<<a[i][j]<<" ";
}
cout<<endl;
}
return 0;
}
There is how the output looks like:
I am trying to make this shape from the code below. I'm confused as to how to make it print the 2nd row, second to last star without it skipping and printing the extra space before printing the star. Once that is figured out would the bottom half, when the stars expands back out, would the code be similar to the top half? I have tried a couple combinations of code between c and r but I have been stuck with what I currently.
---------------------- //row 0
* *| //row 1
* * * *| //row 2
* * * * * *|
* * * * * * * *|
* * * * * * * * * *|
* * * * * * * * * * *|
* * * * * * * * * *|
* * * * * * * *|
* * * * * *|
* * * *|
* *|
----------------------
#include <iostream>
using std::cout; using std::cin; using std::endl;
int main() {
cout << "Enter a positive odd number less than 40: ";
int num = 0;
int z = 1;
for (int a = 0; a < 3; ++a)
{
cin >> num;
if (num < 38 && num > 0 && num % 2 == 1)
{
cout << "Thank you!" << endl << endl;
for (int r = 0; r < num; ++r) //outer loop/rows
{
for (int c = 0; c < num; ++c) //inner loop/columns
{
if (r == 0) cout << "--"; //top of square
else if (c >= r + r - c && c < num - 1)
cout << " ";
//else if (c == num - 1) cout << "*|";
else if (r == num - 1) cout << "--"; //bottom of square
else if (c == num - 1) cout << "*|"; //right side of square
else if (r > c) cout << "* ";
}
cout << endl;
}
break;
}
else cout << "Please enter a positve odd number that is less than 40!" << endl;
}
cout << endl;
}
I just took two variables left=0 & right=num-1 and increased left & decreased right till r<=num/2, after that i reversed the process,when the col <= left or col >=right I printed *.
I hope it will be easy to understand.
Here is the code:
#include <iostream>
using std::cout; using std::cin; using std::endl;
int main() {
cout << "Enter a positive odd number less than 40: ";
int num = 0;
int z = 1;
for (int a = 0; a < 3; ++a)
{
cin >> num;
if (num < 38 && num > 0 && num % 2 == 1)
{
cout << "Thank you!" << endl << endl;
int left=0,right=num-1;
//for printing top line
for(int i = 0; i < num; i++) cout<<"- ";
cout<<"-"<<endl;
for (int r = 0; r < num; ++r) //outer loop/rows
{
//printing columns
for(int c = 0; c < num; c++)
{
if(c <= left || c >= right)
cout<<"* ";
else
cout<<" ";
}
if(r >= num/2) //checking for half of the rows
{
left--;right++;
}
else
{
left++;right--;
}
cout<<"|"<<endl;
}
//for printing last additional line
for(int i = 0; i < num; i++) cout<<"- ";
cout<<"-"<<endl;
break;
}
else cout << "Please enter a positve odd number that is less than 40!" << endl;
}
cout << endl;
}
This approach does it the math way.
Furthermore it draws a full frame with plus-chars at the edges.
Give it a try.
#include <iostream>
#include <cmath>
using std::cout; using std::cin; using std::endl;
int main() {
cout << "Enter a positive odd number less than 40: ";
int num = 0;
int z = 1;
for (int a = 0; a < 3; ++a) {
cin >> num;
if (num < 40 && num > 0 && num % 2 == 1) {
cout << "Thank you!" << endl << endl;
int center = ceil(num / 2.0);
for (int r = 0; r <= num+1; ++r) { //outer loop/rows
for (int c = 0; c <= num+1; ++c) { //inner loop/columns
if (r == 0 || r == num+1) {
if (c == 0 || c == num+1)
cout << "+"; // corner
else
//top or botton of square between corners
if (c == center)
cout << "-";
else
cout << "--";
}
else if (c == 0 || c == num+1) {
cout << "|"; // left or right frame
} else {
// inner part
if ((center-std::abs(center-r)) >= center-std::abs(center-c))
if (c < center)
cout << "* ";
else if (c > center)
cout << " *";
else
cout << "*";
else
if (c == center)
cout << " ";
else
cout << " ";
}
}
cout << endl;
}
} else
cout << "Please enter a positve odd number that is less than 40!" << endl;
}
cout << endl;
}
Just another way (with some more user input checking):
#include <iostream>
#include <string>
#include <limits>
#include <sstream>
using std::cout;
using std::cin;
using std::string;
const auto ssmax = std::numeric_limits<std::streamsize>::max();
const int max_dim = 40;
const int max_iter = 3;
int main() {
cout << "Enter a positive odd number less than " << max_dim << ": ";
int num = 0, counter = 0;
while ( counter < max_iter ) {
cin >> num;
if ( cin.eof() )
break;
if ( cin.fail() ) {
cout << "Please, enter a number!\n";
cin.clear();
cin.ignore(ssmax,'\n');
}
if ( num < max_dim && num > 0 && num % 2 ) {
cout << "Thank you!\n\n";
//top line
string line(num * 2, '-');
cout << line << '\n';
for ( int r = 0, border = num - 1; r < num; ++r ) {
cout << '*';
for ( int c = 1; c < num; ++c ) {
if ( (c > r && c < border) || (c < r && c > border) )
cout << " ";
else
cout << " *";
}
// right border
cout << "|" << '\n';
--border;
}
//bottom line
cout << line << '\n';
++counter;
} else {
cout << "Please, enter a positive odd number that is less than 40!\n";
}
}
cout << std::endl;
}
Or my favorite:
// top line
string line = string(num * 2, '-') + '\n';
cout << line;
// inside lines
int r = 0, border = ( num - 1 ) * 2;
string inside = string(border + 1, ' ') + "|\n";
// top
while ( r < border ) {
inside[r] = '*';
inside[border] = '*';
r += 2;
border -= 2;
cout << inside;
}
// center line
inside[r] = '*';
cout << inside;
// bottom
while ( border > 0 ) {
inside[r] = ' ';
inside[border] = ' ';
r += 2;
border -= 2;
cout << inside;
}
//bottom line
cout << line;
I have to write out a list of prime numbers from 1-100, using a function we have previously wrote, to a file. The commented out part isn't anything related; it's just the previous code we used for the function. I don't know exactly what's going on because the file isn't even being created, and the part inside the for loop is executing with just 2's, 100 times.
#include <iostream>
#include <fstream>
using namespace std;
bool isPrime(int);
int main () {
ofstream outputFile;
int p = 2;
cout << "I will be giving you the first 100 prime numbers " << endl;
cout << "And giving you a file containing those numbers." << endl;
outputFile.open("PrimeNumbers100.txt");
for (int i = 2; i <= 100; i++)
{
isPrime(p);
cout << p << endl;
outputFile << p << endl;
}
outputFile.close();
cout << "You should now have the file." << endl;
/* int n;
int counter = 0;
int p = 2;
cout << "Welcome to prime counter. " << endl;
cout << "Which prime number would you like? ";
cin >> n;
while (counter < n) {
if (isPrime(p)) {
counter++;
}
p++;
}
p = p - 1;
cout << "Prime number " << n << " is " << p << "." << endl;
*/
return 0;
}
bool isPrime(int p) {
bool result = true;
if (p < 2) {
result = false;
}
else {
int stop = (int) (sqrt(p + .5));
for (int d = 2; d <= stop; d++) {
if (p % d == 0) {
result = false;
break;
}
}
}
return result;
}
Could someone please explain what I'm doing wrong here, and why it isn't even creating the file?
You initialize p at the top with 2. You should be calling isPrime with i instead.
You're getting 2s because you're printing out and storing p, but the loop is going over i.
Here is the updated code. Upon research I did find where it was saving the files, and there are instances of it just not working at all. However, This code runs and does give me everything I need it to.. Thank you for the tips, and I appreciate the very.... constructive feedback.
#include <iostream>
#include <fstream>
using namespace std;
bool isPrime(int);
int main () {
ofstream outputFile;
cout << "I will be giving you the first 100 prime numbers " << endl;
cout << "And giving you a file containing those numbers." << endl;
outputFile.open("PrimeNumbers100.txt");
for (int i = 2; i <= 100; i++)
{
if (isPrime(i)) {
outputFile << i << endl;
}
}
outputFile.close();
cout << "You should now have the file." << endl;
return 0;
}
bool isPrime(int p) {
bool result = true;
if (p < 2) {
result = false;
}
else {
int stop = (int) (sqrt(p + .5));
for (int d = 2; d <= stop; d++) {
if (p % d == 0) {
result = false;
break;
}
}
}
return result;
}