have problem with filling array from Serial.
So basically, first asking for lenght of array, then should input from keyborad all elements. Problem is that it's not waiting to enter values into Serial and just fill with 0. If will type values right away, it will put them into array.
My question is how to force wait from Arduino till i will input values.
Thank You!
boolean fill = false;
int sum = 0;
int lengthOfArray;
void setup()
{
Serial.begin(9600);
Serial.print("Set lenght of array : ");
}
void loop()
{
if(fill == false)
{
if(Serial.available() > 0)
{
lengthOfArray = Serial.parseInt();
Serial.println(lengthOfArray);
int tab[lengthOfArray];
for(int i = 0; i < lengthOfArray; i++)
{
delay(10);
Serial.print("Tab[" + String(i) + "] : ");
tab[i] = Serial.parseInt();
Serial.println(tab[i]);
sum += tab[i];
}
fill = true;
Serial.println("Sum = " + String(sum));
}
}
}
If I understood your problem correctly, you're willing to print all the values at once, not for every value that you type.
You may maintain separate for-loops for reading and then printing
for(int i = 0; i < lengthOfArray; i++)
{
delay(10);
Serial.print("Tab[" + String(i) + "] : ");
tab[i] = Serial.parseInt();
sum += tab[i];
}
fill = true;
for(int i = 0; i < lengthOfArray; i++)
Serial.println(tab[i]);
Serial.println("Sum = " + String(sum));
Related
It obviously only makes half a triangle but I don't know how to fix that.
I'm new to this and honestly don't really know how to work it, so help would be greatly appreciated.
I got this far but now I'm lost:
void setup()
{
Serial.begin(9600);
Serial.setTimeout(100000); // timeout now is 100 seconds
// read a number from serial port
String s = Serial.readStringUntil(10); // read a line from serial port
int n = s.toInt(); // convert the input string to integer value
for (int i=0; i<n; i++){
for (int j=0; j<i+1; j++){
Serial.print("*" );
}
Serial.print("\n");
}
}
void loop(){
}
replace n with rows
for(int i = 1, k = 0; i <= rows; ++i, k = 0)
{
for(space = 1; space <= rows-i; ++space)
{
cout <<" ";
}
while(k != 2*i-1)
{
cout << "* ";
++k;
}
cout << endl;
}
here the output
https://ideone.com/OPMeO1
Homework: I'm just stumped as hell. I have algorithms set up, but I have no idea how to code this
Just to be clear you do not need arrays or to pass variables by reference.
The purpose of the project is to take a problem apart and using Top-Down_Design or scratch pad method develop the algorithm.
Problem:
Examine the numbers from 2 to 10000. Output the number if it is a Dual_Prime.
I will call a DualPrime a number that is the product of two primes. Ad where the two primes are not equal . So 9 is not a dual prime. 15 is ( 3 * 5 ) .
The output has 10 numbers on each line.
My Algorithm set-up
Step 1: find prime numbers.:
bool Prime_Number(int number)
{
for (int i = 2; i <= sqrt(number); i++)
{
if (number % 1 == 0)
return false;
}
return true;
}
Step 2: store prime numbers in a array
Step 3: Multiply each array to each other
void Multiply_Prime_Numbers(int Array[], int Size)
{
for (int j = 0; j < Size- 1; j++)
{
Dual_Prime[] = Arr[j] * Arr[j + 1]
}
}
Step 4: Bubble sort
void Bubble_Sort(int Array[], int Size) // Sends largest number to the right
{
for (int i = Size - 1; i > 0; i--)
for (int j = 0; j < i; j++)
if (Array[j] > Array[j + 1])
{
int Temp = Array[j + 1];
Array[j + 1] = Array[j];
Array[j] = Temp;
}
}
Step 5: Display New Array by rows of 10
void Print_Array(int Array[], int Size)
{
for (int i = 0; i < Size; i++)
{
cout << Dual_Prime[i] << (((j % 10) == 9) ? '\n' : '\t');
}
cout << endl;
}
I haven't learned dynamic arrays yet,
Although dynamic arrays and the sieve of Eratosthenes are more preferable, I tried to write minimally fixed version of your code.
First, we define following global variables which are used in your original implementation of Multiply_Prime_Numbers.
(Please check this post.)
constexpr int DP_Size_Max = 10000;
int DP_Size = 0;
int Dual_Prime[DP_Size_Max];
Next we fix Prime_Number as follows.
The condition number%1==0 in the original code is not appropriate:
bool Prime_Number(int number)
{
if(number<=1){
return false;
}
for (int i = 2; i*i <= number; i++)
{
if (number % i == 0)
return false;
}
return true;
}
In addition, Multiply_Prime_Numbers should be implemented by double for-loops as follows:
void Multiply_Prime_Numbers(int Array[], int Size)
{
for (int i = 0; i < Size; ++i)
{
for (int j = i+1; j < Size; ++j)
{
Dual_Prime[DP_Size] = Array[i]*Array[j];
if(Dual_Prime[DP_Size] >= DP_Size_Max){
return;
}
++DP_Size;
}
}
}
Then these functions work as follows.
Here's a DEMO of this minimally fixed version.
int main()
{
int prime_numbers[DP_Size_Max];
int size = 0;
for(int j=2; j<DP_Size_Max; ++j)
{
if(Prime_Number(j)){
prime_numbers[size]=j;
++size;
}
}
Multiply_Prime_Numbers(prime_numbers, size);
Bubble_Sort(Dual_Prime, DP_Size);
for(int i=0; i<DP_Size;++i){
std::cout << Dual_Prime[i] << (((i % 10) == 9) ? '\n' : '\t');;
}
std::cout << std::endl;
return 0;
}
The Sieve of Eratosthenes is a known algorithm which speeds up the search of all the primes up to a certain number.
The OP can use it to implement the first steps of their implementation, but they can also adapt it to avoid the sorting step.
Given the list of all primes (up to half the maximum number to examine):
Create an array of bool as big as the range of numbers to be examined.
Multiply each distinct couple of primes, using two nested loops.
If the product is less than 10000 (the maximum) set the corrisponding element of the array to true. Otherwise break out the inner loop.
Once finished, traverse the array and if the value is true, print the corresponding index.
Here there's a proof of concept (implemented without the OP's assignment restrictions).
// Ex10_TwoPrimes.cpp : This file contains the 'main' function. Program execution begins and ends there.
#include "pch.h"
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
void Homework_Header(string Title);
void Do_Exercise();
void Sieve_Of_Eratosthenes(int n);
void Generate_Semi_Prime();
bool Semi_Prime(int candidate);
bool prime[5000 + 1];
int main()
{
Do_Exercise();
cin.get();
return 0;
}
void Do_Exercise()
{
int n = 5000;
Sieve_Of_Eratosthenes(n);
cout << endl;
Generate_Semi_Prime();
}
void Sieve_Of_Eratosthenes(int n)
{
// Create a boolean array "prime[0..n]" and initialize
// all entries it as true. A value in prime[i] will
// finally be false if i is Not a prime, else true.
memset(prime, true, sizeof(prime));
for (int p = 2; p*p <= n; p++)
{
// If prime[p] is not changed, then it is a prime
if (prime[p] == true)
{
// Update all multiples of p
for (int i = p * p; i <= n; i += p)
prime[i] = false;
}
}
}
bool Semi_Prime(int candidate)
{
for (int index = 2; index <= candidate / 2; index++)
{
if (prime[index])
{
if (candidate % index == 0)
{
int q = candidate / index;
if (prime[q] && q != index)
return true;
}
}
}
return false;
}
void Generate_Semi_Prime()
{
for (int i = 2; i <= 10000; i++)
if (Semi_Prime(i)) cout << i << "\t";
}
Beginner here, and I'm stuck. The main program is provided to us, and we're supposed to write 3 functions. readBig(), addBig(), and printBig(). I'm stuck on the addBig() function. It's supposed to sum two arrays, and perform the carry operation. I cannot figure out where I'm going wrong. The carry operation is working out for me.
Any help/direction is appreciated.
#include <iostream>
using namespace std;
//This program will test three functions capable of reading, adding,
//and printing 100-digit numbers.
// Do not change these function prototypes:
void readBig(int[]);
void printBig(int[]);
void addBig(int[], int[], int[]);
// This constant should be 100 when the program is finished.
const int MAX_DIGITS = 100;
//There should be no changes made to the main program when you turn it
in.
int main(){
// Declare the three numbers, the first, second and the sum:
int num1[MAX_DIGITS], num2[MAX_DIGITS], sum[MAX_DIGITS];
bool done = false;
char response;
while (not done)
{
cout << "Please enter a number up to "<<MAX_DIGITS<< " digits: ";
readBig(num1);
cout << "Please enter a number up to "<<MAX_DIGITS<< " digits: ";
readBig(num2);
addBig(num1, num2, sum);
printBig(num1);
cout << "\n+\n";
printBig(num2);
cout << "\n=\n";
printBig(sum);
cout << "\n";
cout <<"test again?";
cin>>response;
cin.ignore(900,'\n');
done = toupper(response)!='Y';
}
return 0;
}
//ReadBig will read a number as a string,
//It then converts each element of the string to an integer and stores
it in an integer array.
//Finally, it reverses the elements of the array so that the ones digit
is in element zero,
//the tens digit is in element 1, the hundreds digit is in element 2,
etc.
void readBig(int num[])
{
for(int i = 0; i < MAX_DIGITS; i++){
num[i] = 0;
}
string numStr;
getline(cin,numStr);
string temp;
//store into array
for (int i = 0; i < numStr.length(); i++){
temp = numStr.at(i);
num[i] = stoi(temp);
}
int arrayLength = MAX_DIGITS;
int temp2;
for (int i = 0; i < (arrayLength/2); i++){
temp2 = num[i];
num[i] = num[(arrayLength - 1) - i];
num[(arrayLength - 1) - i] = temp2;
}
}
//AddBig adds the corresponding digits of the first two arrays and
stores the answer in the third.
//In a second loop, it performs the carry operation.
void addBig(int num1[], int num2[], int sum[])
{
for (int i = 0; i < MAX_DIGITS; i++){
sum[i] = num1[i] + num2[i];
if (sum[i] > 9){
sum[i] = sum[i] - 10;
sum[i+1] = sum[i+1] + 10;
}
}
}
//PrintBig uses a while loop to skip leading zeros and then uses a for
loop to print the number.
void printBig(int array[])
{
int i = 0;
while (array[i] == 0){
i++;
}
for (int j = i; j < MAX_DIGITS;j++){
cout << array[j] << endl;
}
}
Looks like readBig function isn't correct, it stores least significiant digit into num[numStr.length()-1], after reversing it became num[MAX_DIGITS -1 - ( numStr.length()-1], but addNum assumes last digit is num[0].
Correct variant:
void readBig(int num[])
{
//clear num, read numStr...
//store into array
int count = 0;
for (int i = numStr.length()-1; i >= 0; --i){
temp = numStr.at(i);
num[count++] = stoi(temp);
}
|
So this
sum[i] = sum[i] - 10;
sum[i+1] = sum[i+1] + 10;
should most likely be this
sum[i] = sum[i] - 10;
sum[i+1] = sum[i+1] + 1;
Since its the next decimal place it shouldnt be incremented by 10
Also when you get to the last cell in your array
sum[i+1] = sum[i+1] + 1;
this will be out of bounds, so depending on the requirments you will want to change this
Currently studying software engineering at college (first year) and made a program where the user enters how many entries there will be and then they input the times for each entry and it is sorted in descending order.
The problem I am having is when I enter a large number for the first input it doesn't sort correctly but the rest do. It would be great if someone could help me out with this and sorry for the noob question:P
The entire code:
#include "stdafx.h"
#include <iostream>
using namespace std;
int TotalSize = 0;
void getSpeed(int *CalculationTime, int NoOfCalculations)
{
for (int i = 0; i < NoOfCalculations; i++)
{
cout << "Please enter the speed of calculation " << i + 1 << "(Ms): "; cin >> CalculationTime[i];
}
}
void sort_speeds(int *CalculationTime, int NoOfCalculations)
{
// Sorting speeds in decending order
bool swapped = true;
int i, j = 0;
int temp;
while (swapped)
{
swapped = false;
j++;
for (i = 1; i < NoOfCalculations - j; i++)
{
if (CalculationTime[i] > CalculationTime[i + 1])
{
temp = CalculationTime[i];
CalculationTime[i] = CalculationTime[i + 1];
CalculationTime[i + 1] = temp;
swapped = true;
}
}
}
// Output times decending order
for (int i = 0; i < NoOfCalculations; i++)
{
cout << CalculationTime[i] << "\n";
}
}
int main()
{
// Declaring & Initializing variables
int NoOfCalculations = 0;
int *CalculationTime = new int[NoOfCalculations];
// Getting user input
cout << "How many calculations are there? "; cin >> NoOfCalculations;
getSpeed(CalculationTime, NoOfCalculations);
// Sorting and displaying times
sort_speeds(CalculationTime, NoOfCalculations);
system("pause");
return 0;
}
You've never compare first element of your array with anything - for (i = 1; i < NoOfCalculations - j; i++) should be for (i = 0; i < NoOfCalculations - j; i++)
The issue is for (i = 1; i < NoOfCalculations - j; i++) You are starting at position 1, start at position 0 and it fixes the problem. for (i = 0; i < NoOfCalculations - j; i++)
// Declaring & Initializing variables
int NoOfCalculations = 0;
int *CalculationTime = new int[NoOfCalculations];
// Getting user input
cout << "How many calculations are there? "; cin >> NoOfCalculations;
Bzzzt. You allocate a zero-element array, and then don't reallocate it. I bet if you entered a large enough number for your number of calculations, your program would crash.
Really, you want to be using std::vector, an extremely useful datastructure, the use of which is a bit outside of the scope of this answer. Basically, you can do stuff like this:
std::vector<int> getSpeeds(int NoOfCalculations)
{
std::vector<int> speeds;
for (int i = 0; i < NoOfCalculations; i++)
{
int speed;
std::cout << "Please enter the speed of calculation " << i + 1 << "(Ms): ";
std::cin >> speed;
speeds.push_back(speed);
}
return speeds;
}
You can use the returned vector almost exactly as if it were an array:
std::vector<int> speeds = getSpeeds(10);;
if (CalculationTime[3] > CalculationTime[4])
// do something
Often, in a C++ application, the explicit use of pointers is a sign that you're not using the standard library, and as a result making life much, much harder for yourself.
Oh, and also:
for (i = 1; i < NoOfCalculations - j; i++)
You never look at NoOfCalculations[0] or NoOfCalculations[i - 1], so you never touch the first element.
while (swapped)
{
swapped = false;
j++;
for (i = 0; i < NoOfCalculations - j; i++) //try and start i from 0. I think you are missing the first element to check
{
if (CalculationTime[i] > CalculationTime[i + 1])
{
temp = CalculationTime[i];
CalculationTime[i] = CalculationTime[i + 1];
CalculationTime[i + 1] = temp;
swapped = true;
}
}
}
I've got this small piece of code
int row[7];
bool equals = false;
std::vector<int>range;
for(int i = 1; i <= 35; ++i)
{
range.push_back(i);
}
for(int i = 0; i < 7; i++){
int number = range[rand() % range.size() + 1];
std::vector<int>::iterator pos = find(range.begin(), range.end(), number);
row[i] = number;
range.erase(range.begin() + (*pos - 1));
std::cout << row[i] << endl;
}
return 0;
It takes away random elements from the vector, the problem I've got is that every time I remove a object from the vector the size updates but the positions doesn't seem to change on the individual numbers in the vector, making the program crash since I sometimes travel outside the bounds of the vector.
I've tried with vector::shrink_to_fit but it didn't seem to re-evaluate the vectors item positions.
What am I missing? It seems like such a simple thing to do but I just can't wrap my head around it.
P.S
I'm a c++ scrub so if you have any input on the code being bad/unsafe I'm open for suggestions/constructive criticism.
rand() % range.size() + 1
can go outside the bounds of the vector
use
rand() % range.size()
use this piece of code instead :
std::vector<int>range;
for(int i = 1; i <= 35; ++i)
{
range.push_back(i);
}
srand(time(0)) ;
for(int i = 0; i < 7; i++){
int index = rand() % range.size() ;
int number = range[index];
row[i] = number;
range.erase(range.begin() + index);
std::cout << row[i] << endl;
}