I have a serious problem that I just can't seem to solve. I apologize if it's a really newbie-like problem.
srand(117);
//enumeration type to keep track of which fish is which
enum CellState {EMPTY, FISH, SHARK};
//Creating the grid
CellState fishGrid[MAX_X][MAX_Y];
for(int m = 0; m < MAX_X; ++m)
{
for(int n = 0; n < MAX_Y; ++n)
{
int num = rand() % 2;
if(num == 0)
fishGrid[m][n] = EMPTY;
else
{
num = rand() % 2;
if(num == 0)
fishGrid[m][n] = SHARK;
else
fishGrid[m][n] = FISH;
}
}
}
//calculate how many on grid
if(stepsTaken % 5 == 0)
{
int fishAmount = 0;
int sharkAmount = 0;
for(int m = 0; m < MAX_X; m++)
{
for(int n = 0; n < MAX_Y; n++)
{
if(fishGrid[m][n] = FISH)
fishAmount++;
else if(fishGrid[m][n] = SHARK)
sharkAmount++;
}
}
cout << "FISH: " << fishAmount << endl
<< "SHARKS: " << sharkAmount << endl << endl;
For some reason, the output is always:
FISH: 100
SHARKS: 0
I don't necessarily understand. Would someone be able to please help me? Thanks.
= designates assignment operator in C++. Which means that what you have here
if(fishGrid[m][n] = FISH)
fishAmount++;
else if(fishGrid[m][n] = SHARK)
sharkAmount++;
uses assignment operator inside if conditions. By the above you override your entire grid with FISH values.
Equality comparison in C++ is performed by == operator. But you already know that, since you already use == in your num comparisons. Why are you using = in these grid comparisons then?
Related
So basically I am trying to create a loop that fills a matrix with random numbers. I need to make it so every column has a different range, unique to it.
//Variables
int lsx = 3;
int lsy = 10;
int lust[lsy][lsx];
int i = 0;
int l = 0;
int shpp = 7;
//List setup
for (i = 0; i < lsy; i++)
{
for (l = 0; l < lsx; l++)
{
lust[i][l] = 0;
}
}
while (true)
{
//List generator
for (i = 0; i < lsy; i++)
{
for (l = 0; l < lsx; l++)
{
//Column 1
if (i == 0)
{
lust[i][l] = rand() % flx;
cout << lust[i][l] << '\n';
}
//Column 2
if (i == 1)
{
lust[i][l] = rand() % fly;
cout << lust[i][l] << '\n';
}
//Column 3
if (i == 2)
{
lust[i][l] = rand() % shpp;
cout << lust[i][l] << '\n';
}
}
cout << "Endline reached! \n \n";
}
for (i = 0; i < lsy; i++)
{
for (l = 0; l < lsx; l++)
{
cout << lust[i][l] << " ";
}
cout << "\n";
}
}
}
This only generates 3 lines. Does anyone have any ideas on why this could happen?
I tried changing some stuff around but only got weirder results that wouldn't fill the array in completely eitherThis is what the program displays when I try and run it
for (l = 0; l < lsx; l++)
{
Column 1
if (i == 0)
}
lust[i][l] = rand() % flx;
cout << lust[i][l] << '\n';
}
Column 2
if (i == 1)
}
lust[i][l] = rand() % fly;
cout << lust[i][l] << '\n';
}
Column 3
if (i == 2)
{
lust[i][l] = rand() % shpp;
cout << lust[i][l] << '\n';
}
}
cout << "Endline reached! \n \n";
You're using i (the line iterator) to evaluate what you're going to fill. Which means your code will only concern itself with lines 0, 1 and 2. Instead, shift that i to l - your column iterator. It should work.
Also, consider removing the while true loop. Not only is it redundant, it's also pretty dangerous considering there's no break condition - in this case it's safe, since you'll be around to shut it down, but as a good practice stay out of while(true) unless you can't write your break condition as a boolean expression
I'm trying to convert an histogram with absolute values to an histogram showing the relative frequency of letters in a string, written by the user. The letters frequency should be represented by *. So, if the letter "A" is 1% of a string, there should be two *. 1% = two *.
When trying to calculate the frequency, the output is zero. I don't really understand why.
I've tried to search the internet, but I can't really find something that helps me. I guess I'm stuck, both in my head and coding.
This is the code for my three functions:
void berakna_histogram_abs(const string inm, int arr[ANTAL_BOKSTAVER]){
int i, j = 0;
while (inm[i] != '\0'){
if (inm[i] >= 'a' && inm[i] <= 'z'){
j = inm[i] - 'a';
++arr[j];
}
if (inm[i] >= 'A' && inm[i] <= 'Z'){
j = inm[i] - 'A';
++arr[j];
}
i++;
}
}
void abs_till_rel(int arr[ANTAL_BOKSTAVER], int (&ree)[ANTAL_BOKSTAVER]){
for(int i = 0; i < ANTAL_BOKSTAVER; i++) {
ree[i] = arr[i] / 26;
printf("%c %lf \n", i + 'a', ree[i]);
}
for (int x = 0; x < ANTAL_BOKSTAVER; x++){
}
}
void plotta_histogram_rel(int (&ree)[ANTAL_BOKSTAVER]){
cout << "Frekvensen av bokstäver i texten är: " << endl;
for (int i = 0; i < ANTAL_BOKSTAVER; i++){
cout << char(i + 'a') << " : " << ree[i] << endl;
}
}
I'm not allowed to do any calculations in the third function, that is only for writing the histogram. The whole program is pretty big, if you'd like, I'll provide all the code.
Any help forward is much appreciated.
Thanks!
So, you have some errors that need to be corrected. You do not pass the array as reference in the first function. You pass it by value. So all modifications that will be done to that arra in the first function berakna_histogram_abs will not be visible to the outside world.
You need to do the same as in you other functions -->
void berakna_histogram_abs(const std::string inm, int (&arr)[ANTAL_BOKSTAVER]) {
By the way, the string should also be passed as reference. Anyway. Not so important.
Next problem. You forgot to initialize variable i to 0 in your first function. So, it will have some random value and the program will fail, becuase you access some random index with inm[i].
In your calculation function abs_till_rel you are using the wrong formular. You need to multiply with 100 to get integer results between 0 and 100 for the percentage. And you divide by 26, which makes the result relative to the amount of the number of letters in an alphabet. My guess is that you want to have the relations to the number of letters in the string.
For that, you first need to calculate all counts of letters to get the overall count. Like for example with:
int sum = 0;
for (int i = 0; i < ANTAL_BOKSTAVER; i++) sum += arr[i];
and then divide by this sum, like so:
ree[i] = (arr[i] * 100) / sum;
And to output the histogram, you can simply build a string with stars, using the std::string constructor number 2
Your updated program would look like this:
#include <iostream>
#include <string>
#include <stdio.h>
constexpr int ANTAL_BOKSTAVER = 26;
void berakna_histogram_abs(const std::string inm, int (&arr)[ANTAL_BOKSTAVER]) {
int i = 0, j = 0;
while (inm[i] != '\0') {
if (inm[i] >= 'a' && inm[i] <= 'z') {
j = inm[i] - 'a';
++arr[j];
}
if (inm[i] >= 'A' && inm[i] <= 'Z') {
j = inm[i] - 'A';
++arr[j];
}
i++;
}
}
void abs_till_rel(int arr[ANTAL_BOKSTAVER], int(&ree)[ANTAL_BOKSTAVER]) {
int sum = 0;
for (int i = 0; i < ANTAL_BOKSTAVER; i++) sum += arr[i];
if (sum >0) for (int i = 0; i < ANTAL_BOKSTAVER; i++) {
ree[i] = (arr[i] * 100) / sum;
std::cout << (char)(i + 'a') << '\t' << ree[i] << '\n';
}
for (int x = 0; x < ANTAL_BOKSTAVER; x++) {
}
}
void plotta_histogram_rel(int(&ree)[ANTAL_BOKSTAVER]) {
std::cout << "Frekvensen av bokstäver i texten är: " << std::endl;
for (int i = 0; i < ANTAL_BOKSTAVER; i++) {
std::cout << char(i + 'a') << " : " << std::string(ree[i]*2,'*') << std::endl;
}
}
int main() {
std::string test{"The quick brown fox jumps over the lazy dog"};
int frequencyArray[ANTAL_BOKSTAVER] = {};
int frequencyInPercent[ANTAL_BOKSTAVER] = {};
berakna_histogram_abs(test, frequencyArray);
abs_till_rel(frequencyArray, frequencyInPercent);
plotta_histogram_rel(frequencyInPercent);
}
But in C++, we would use the standard approach and write the followin:
#include <iostream>
#include <map>
#include <string>
#include <cctype>
// Our test string. This is a standard test string that contains all letters
std::string test{ "The quick brown fox jumps over the lazy dog" };
int main() {
// Count all letters
std::map<char, size_t> counter{};
for (const auto& c : test) if (std::isalpha(c)) counter[std::tolower(c)]++;
// Show histogram
for (const auto& [letter, count] : counter)
std::cout << letter << '\t' << std::string((count * 200) / test.size(), '*') << '\n';
return 0;
}
void abs_till_rel(int arr[ANTAL_BOKSTAVER], int langd, double frekArr[ANTAL_BOKSTAVER]){
//Function to calculate the relative frequency of letters in a string.
for (int i = 0; i < ANTAL_BOKSTAVER; i++){
frekArr[i] = arr[i]; //Writes over the input from the user to a new array.
frekArr[i] = frekArr[i] * 200 / langd; //Calculates the relative frequency
//*200 since 1% should be represented by two (2) *.
}
}
void plotta_histogram_rel(double frekArr[ANTAL_BOKSTAVER], int langd){
int j = 0;
for (int i = 0; i < ANTAL_BOKSTAVER; i++){
cout << char(i + 'A') << " : ";
//Creates a histograg, horizontal, with A-Z.
if(frekArr[i] > 0){
for ( j = 0; j < frekArr[i]; j++){
cout << "*";
}
cout << endl;
}
//If the index in frekArr is NOT empty, loop through the index [i] times and
//write double the amount of *.
else {
cout << " " << endl;
//Else, leave it empty.
}
}
}
I've solved the issue. See the working code above.
I'm trying to get all prime numbers in the range of 2 and the entered value using this c++ code :
#include<iostream>
using namespace std;
int main() {
int num = 0;
int result = 0;
cin >> num;
for (int i = 2; i <= num; i++) {
for (int b = 2; b <= num; b++) {
result = i % b;
if (result == 0) {
result = b;
break;
}
}
cout << result<< endl <<;
}
}
the problem is that I think am getting close to the logic, but those threes and twos keep showing up between the prime numbers. What am I doing wrong?
I've fixed your code and added comments where I did the changes
The key here is to understand that you need to check all the numbers smaller then "i" if one of them dividing "i", if so mark the number as not prime and break (the break is only optimization)
Then print only those who passed the "test" (originally you printed everything)
#include <iostream>
using namespace std;
#include<iostream>
using namespace std;
int main()
{
int num = 0;
int result = 0;
cin >> num;
for (int i = 2; i <= num; i++) {
bool isPrime = true; // Assume the number is prime
for (int b = 2; b < i; b++) { // Run only till "i-1" not "num"
result = i % b;
if (result == 0) {
isPrime = false; // if found some dividor, number nut prime
break;
}
}
if (isPrime) // print only primes
cout << i << endl;
}
}
Many answers have been given which explains how to do it. None have answered the question:
What am I doing wrong?
So I'll give that a try.
#include<iostream>
using namespace std;
int main() {
int num = 0;
int result = 0;
cin >> num;
for (int i = 2; i <= num; i++) {
for (int b = 2; b <= num; b++) { // wrong: use b < i instead of b <= num
result = i % b;
if (result == 0) {
result = b; // wrong: why assign result the value of b?
// just remove this line
break;
}
}
cout << result<< endl <<; // wrong: you need a if-condtion before you print
// if (result != 0) cout << i << endl;
}
}
You have multiple errors in your code.
Simplest algorithm (not the most optimal though) is for checking whether N is prim is just to check whether it doesn't have any dividers in range [2; N-1].
Here is working version:
int main() {
int num = 0;
cin >> num;
for (int i = 2; i <= num; i++) {
bool bIsPrime = true;
for (int b = 2; bIsPrime && b < i; b++) {
if (i % b == 0) {
bIsPrime = false;
}
}
if (bIsPrime) {
cout << i << endl;
}
}
}
I would suggest pulling out the logic of determining whether a number is a prime to a separate function, call the function from main and then create output accordingly.
// Declare the function
bool is_prime(int num);
Then, simplify the for loop to:
for (int i = 2; i <= num; i++) {
if ( is_prime(i) )
{
cout << i << " is a prime.\n";
}
}
And then implement is_prime:
bool is_prime(int num)
{
// If the number is even, return true if the number is 2 else false.
if ( num % 2 == 0 )
{
return (num == 2);
}
int stopAt = (int)sqrt(num);
// Start the number to divide by with 3 and increment it by 2.
for (int b = 3; b <= stopAt; b += 2)
{
// If the given number is divisible by b, it is not a prime
if ( num % b == 0 )
{
return false;
}
}
// The given number is not divisible by any of the numbers up to
// sqrt(num). It is a prime
return true;
}
I can pretty much guess its academic task :)
So here the think for prime numbers there are many methods to "get primes bf number" some are better some worse.
Erosthenes Sieve - is one of them, its pretty simple concept, but quite a bit more efficient in case of big numbers (like few milions), since OopsUser version is correct you can try and see for yourself what version is better
void main() {
int upperBound;
cin >> upperBound;
int upperBoundSquareRoot = (int)sqrt((double)upperBound);
bool *isComposite = new bool[upperBound + 1]; // create table
memset(isComposite, 0, sizeof(bool) * (upperBound + 1)); // set all to 0
for (int m = 2; m <= upperBoundSquareRoot; m++) {
if (!isComposite[m]) { // if not prime
cout << m << " ";
for (int k = m * m; k <= upperBound; k += m) // set all multiplies
isComposite[k] = true;
}
}
for (int m = upperBoundSquareRoot; m <= upperBound; m++) // print results
if (!isComposite[m])
cout << m << " ";
delete [] isComposite; // clean table
}
Small note, tho i took simple implementation code for Sive from here (writing this note so its not illegal, truth be told wanted to show its easy to find)
#include <cstdlib>
#include <iostream>
#include <Math.h>
#include <algorithm>
#include <string>
#include <iterator>
#include <iostream>
#include <vector> // std::vector
using namespace std;
int stepCount, i, x, y, z, j, k, array1Size, array2Size, tester, checker;
int numstring[10] = { 0,1,2,3,4,5,6,7,8,9 };
int numstringTest[10] = { 0,1,2,3,4,5,6,7,7,9 };
int* numbers;
int* differentNumbers;
int* p;
int* otherNumbers;
void stepCounter(int a) {
// determines the step number of the number
if (a / 10 == 0)
stepCount = 1;
else if (a / 100 == 0)
stepCount = 2;
else if (a / 1000 == 0)
stepCount = 3;
else if (a / 10000 == 0)
stepCount = 4;
else if (a / 100000 == 0)
stepCount = 5;
else if (a / 1000000 == 0)
stepCount = 6;
else if (a / 10000000 == 0)
stepCount = 7;
else if (a / 100000000 == 0)
stepCount = 8;
else if (a / 1000000000 == 0)
stepCount = 9;
}
void stepIndicator(int b) {
// indicates each step of the number and pass them into array 'number'
stepCounter(b);
numbers = new int[stepCount];
for (i = stepCount; i>0; i--) {
//
/*
x = (round(pow(10,stepCount+1-i)));
y = (round(pow(10,stepCount-i)));
z = (round(pow(10,stepCount-i)));
*/
x = (int)(pow(10, stepCount + 1 - i) + 0.5);
y = (int)(pow(10, stepCount - i) + 0.5);
numbers[i - 1] = (b%x - b%y) / y;
}
}
int sameNumberCheck(int *array, int arraySize) {
//checks if the array has two or more of same integer inside return 1 if same numbers exist, 0 if not
for (i = 0; i<arraySize - 1; i++) {
//
for (j = i + 1; j<arraySize; j++) {
//
if (array[i] == array[j]) {
//
return 1;
}
}
}
return 0;
}
void getDifferentNumbers(int* array, int arraySize) {
//
k = 0;
j = 0;
checker = 0;
otherNumbers = new int[10 - arraySize]; //exact number of other numbers is 10 - numbers we have
for (i = 0; i<10; i++) {
if ((i>0)&(checker = 0)) {
k++;
otherNumbers[k - 1] = i - 1;
}
//
checker = 0;
for (j = 0; j<arraySize; j++) {
//
p = array + j;
cout << *p << endl; //ilkinde doğru sonra yanlış yapıyor?!
if (*p = i) {
checker++;
}
}
}
}
int main(int argc, char *argv[])
{
stepCounter(999999);
cout << stepCount << endl;
stepIndicator(826424563);
for (j = 0; j<9; j++) {
//
cout << numbers[j] << endl;
}
cout << sameNumberCheck(numstringTest, 10) << " must be 1" << endl;
cout << sameNumberCheck(numstring, 10) << " must be 0" << endl;
cout << endl;
getDifferentNumbers(numstringTest, 10);
cout << endl;
cout << endl << otherNumbers[0] << " is the diff number" << endl;
system("PAUSE");
return EXIT_SUCCESS;
}
Hi, my problem is with pointers actually. You will see above, function getDifferentNumbers. It simply does a comparement if in any given array there are repeated numbers(0-9). To do that, I passed a pointer to the function. I simply do the comparement via pointer. However, there is a strange thing here. When I execute, first time it does correct, but secon time it goes completely mad! This is the function:
void getDifferentNumbers(int* array, int arraySize) {
//
k = 0;
j = 0;
checker = 0;
otherNumbers = new int[10 - arraySize]; //exact number of other numbers is 10 - numbers we have
for (i = 0; i<10; i++) {
if ((i>0)&(checker = 0)) {
k++;
otherNumbers[k - 1] = i - 1;
}
//
checker = 0;
for (j = 0; j<arraySize; j++) {
//
p = array + j;
cout << *p << endl; //ilkinde doğru sonra yanlış yapıyor?!
if (*p = i) {
checker++;
}
}
}
}
and this is the array I passed into the function:
int numstringTest[10] = {0,1,2,3,4,5,6,7,7,9};
it should give the number 7 in otherNumbers[0], however it does not. And I do not know why. I really can not see any wrong statement or operation here. When I execute, it first outputs the correct values of
numstringTest: 1,2,3,4,5,6,7,7,9
but on next 9 iteration of for loop it outputs:
000000000011111111112222222222333333333344444444445555555555666666666677777777778888888888
You have some basic problems in your code.
There are multiple comparisons that are not really comparisons, they're assignments. See the following:
if((i>0) & (checker=0)){
and
if(*p = i){
In both cases you're assigning values to the variables, not comparing them. An equality comparison should use ==, not a single =. Example:
if (checker == 0) {
Besides that, you're using & (bitwise AND) instead of && (logical AND), which are completely different things. You most likely want && in your if statement.
I've just noticed this:
getDifferentNumbers(numstringTest, 10);
and in that function:
otherNumbers = new int[10 - arraySize];
which doesn't seem right.
This question already has answers here:
Closed 10 years ago.
Possible Duplicate:
How to have C++ solve the equation for an input value?
I'm new to C++ and am just playing around...
#include <iostream>
using namespace std;
int limbs(int handdmg, int armdmg, int chestdmg, int headshot, int legdmg)
{
return handdmg + armdmg + chestdmg + legdmg + headshot;
}
main ()
{
int totaldmg;
int handdmg;
int armdmg;
int chestdmg;
int legdmg;
int headshot;
int Dmgdial;
int x;
// limiting the variables to a smaller range of integers
handdmg = 0 < x < 5;
armdmg = 10 < x < 15;
chestdmg = 25 < x < 50;
legdmg = 30 < x < 40;
headshot = 80 < x < 120;
cout << "Enter your total damage taken:" << endl;
cin >> totaldmg;
Dmgdial = totaldmg;
// want the variables to = the input value in the best smallest way possible
limbs(handdmg, armdmg, chestdmg, headshot, legdmg) = Dmgdial;
// then print the variables answers to the screen
cout << "damage given to the hand: " << handdmg << endl;
cout << "damage given to the arm: " << armdmg << endl;
cout << "damage given to the chest: " << chestdmg << endl;
cout << "damage given to the leg: " << legdmg << endl;
cout << "damage given to the head: " << headshot << endl;
cin.clear();
cin.ignore(2505, '\n');
cin.get();
return 0;
}
So the concept is simple - you enter a value such as 156 into the program and then have the computer calculate the best way to get that value using the limited values of x.
However, limbs(handdmg, armdmg, chestdmg, headshot, legdmg) = Dmgdial doesn't work. It's backwards as far as the compiler is concerned.
How would I get this type of program to work?
[..] the best way to get that value [...]
This is your task. "The computer" doesn't know anything about damage or what a headshot is. Take a paper and write down, how you want to calculate damage details from the total damage value. For example:
struct DamageDetails
{
int head, leg, arm;
const int HEAD_MAX = 120;
const int HEAD_MIN = 80;
static DamageDetails FromTotalDamage(int totalDamage)
{
DamageDetails damage;
int damageTakenSoFar = totalDamage;
damage.head = totalDamage / 2; // 50% damage is taken to head
if (damage.head > HEAD_MAX)
damage.head = HEAD_MAX;
damageTakenSoFar -= damage.head;
// ...
return damage;
}
};
You are trying to solve 1 equation with 5 unknowns, which is an under-determined problem. You need a system of 5 equations with 5 unknowns to get a unique answer.
Moreover, you have not actually specified the equation - right now it just looks like you are assuming a linear equation t = x + y + z + v + w. That's probably not correct, considering the (strange) section you have that is limiting the variables.
Moreover, C++ is not a mathematical system for solving equations. You will need to write the code to solve them yourself, or use an third-party library.
Overall, I would say you are in over your head, as far as the math and the programming expertise needed to do what you are trying to do. You will benefit from learning more theory, before trying a task like this.
Here is a solution for your problem using backtracking:
#include <stdio.h>
int v[100], n, int dmg;
void init(int k)
{
v[k] = 0;
}
bool solutionReached( int k )
{
if (k <= 5)
return false;
int sum = 0;
for (int i = 1; i <= k; i++)
{
sum += v[i];
}
if(sum == dmg)
{
if( v[1] < 5 &&
v[2] > 10 && v[2] < 15 &&
v[3] > 25 && v[3] < 50 &&
v[4] > 30 && v[4] < 40 &&
v[5] > 80 && v[5] < 120)
return true;
}
return false;
}
void printSolution( int k )
{
for (int i = 1; i < k; i++)
{
printf("%i ", v[i]);
}
printf("\n");
}
bool hasSuccesor( int k )
{
if(v[k] < 120 && k <= 5)
{
v[k]++;
return true;
}
return false;
}
bool isValid( int k )
{
/*
if(v[1] > 5)
return false;
if(!(v[2] > 10 && v[2] < 15))
return false;
if(!(v[3] > 25 && v[3] < 50))
return false;
if(!(v[4] > 30 && v[4] < 40))
return false;
if (!(v[5] > 80 && v[5] < 120))
return false;
*/
return true;
}
void bkt(int k)
{
if(solutionReached(k))
printSolution(k);
else
{
init(k);
while(hasSuccesor(k))
if(isValid(k))
bkt(k + 1);
}
}
int main(int argc, char* argv[])
{
dmg = 200;
n = 6;
bkt(1);
return 0;
}