I have a bit of a problem with this. I've tried to create a function to return a random number and pass it to the array, but for some reason, all the numbers generated are "0".
#include <iostream>
#include <ctime>
#include <iomanip>
using namespace std;
int generLosNum(int);
int main()
{
srand(time(NULL));
int LosNum;
const int rozmiar = 10;
int tablica[rozmiar];
for(int i=0; i<rozmiar; i++)
{
tablica[i] = generLosNum(LosNum);
cout << tablica[i] <<" ";
}
return 0;
}
int generLosNum(int LosNum)
{
int LosowyNum;
LosowyNum = (rand() % 10);
return (LosNum);
}
So the return for your int generLosNum(int LosNum) was printing 0 because you had it returning LosNum which was initialized equaling to zero. I changed your code so it works and will print out the 10 random numbers.
#include <iostream>
#include <ctime>
#include <iomanip>
using namespace std;
int generLosNum();
int main()
{
srand(time(NULL));
int LosNum = 0;
const int rozmiar = 10;
int tablica[rozmiar];
for (int i = 0; i < rozmiar; i++)
{
tablica[i] = generLosNum();
cout << tablica[i] << " ";
}
return 0;
}
int generLosNum()
{
int LosowyNum;
LosowyNum = (rand() % 10);
return LosowyNum;
}
Change your method generLosNum to the following and the method signature to int generLosNum() and it should work.
int generLosNum()
{
return (rand() % 10);
}
Reason: As others also mentioned in the comments, you were just returning the number that you passed in as parameter and also the logic for this method doesn't even need a parameter.
Related
I couldn't figure out how to make a function return an array so instead I decided to try and pass an empty array (of the correct size) into my function and than reassign the address to a different array of the same size. Is this at all a way to do things??? Can someone show me what to do? if this is wrong can you fill me in on how to do this?
here is my code:
#include <iostream>
#include <cmath>
using namespace std;
void ArrayFiller(int earray,int s, int f){
int *ptrarray = &earray;
int prenum_size = std::abs(s) + f - 1;
int pre_num[prenum_size];
for(int x=s;x<f;x++){
pre_num[x+std::abs(s)] = x;
}
*ptrarray = pre_num;
}
int Main(){
int first = -10;
int second = 15;
int temp[abs(first) + abs(second)];
ArrayFiller(temp, first, second);
int n = sizeof(temp)/sizeof(temp[0]);
for (int i = 0; i < n; i++) {
cout << temp[i] << ' ';
}
return 0;
}
I think you're looking for something like this:
#include <iostream>
#include <cmath>
using namespace std;
void ArrayFiller(int earray[],int s, int f){
for(int x=s;x<f;x++){
earray[x+(std::abs(s))] = x;
}
}
int main(){
int first = -10;
int second = 15;
int n = abs(first)+abs(second);
int* temp = new int[n];
ArrayFiller(temp, first, second);
for (int i = 0; i < n; i++) {
cout << temp[i] << ' ';
}
delete [] temp;
return 0;
}
I have a program where I want to pass an array - in this case k[arrsize], which is a parameter of the funciton fillArray() to the other function create_file() (the same array, filled with the random numbers). However, I cannot pass the same array and I would like to ask how can this be done?
#include "stdafx.h"
#include <iostream>
#include <fstream>
#include <time.h>
#include <stdlib.h>
using namespace std;
const int arrsize = 20;
//int a[arrsize];
fstream p;
void fillArray(int k[arrsize])
{
srand((unsigned)time(NULL));
for (int i = 0; i<20; i++)
{
if (i % 2 == 0)
{
k[i] = -(rand() % 100);
}
else
{
k[i] = (rand() % 100);
}
}
}
void create_file(int k[arrsize])
{
p.open("danni.dat", ios::out);
for (int i = 0; i<20; i++)
{
p << k[i] << endl;
}
p.close();
}
int main() {
fillArray(k);
create_file(k);
return 0;
}
You simply forget to define an array:
int main() {
int k[arrsize];
fillArray(k);
create_file(k);
}
Usually you don't want to pass the whole array, instead you might want to pass a reference to it. I suggest you to use std::array instead of a C-style arrays.
#include <array>
void fill(std::array<int, 1>& a)
{
a[0] = 0;
}
int main()
{
std::array<int, 1> a = {};
fill(a);
return 0;
}
I want to make a method that generates an array with random values between 0 and 6 in it without repeating those values.
This is what I've got:
void randomArray(){
randNum = rand() % 6;
code[0] = randNum
for (int i = 1; i < 4; i++){
randNum = rand() % 6;
code[i] = randNum;
while (code[i] == code[i - 1]){
randNum = rand() % 6;
code[i] = randNum;
}
}
}
But I'm getting repeated values on the random-generated array.
PD: I also need to use a similar method to make an array of enum's.
You could do something like this:
int randomFromSet(std::vector<int>&_set)
{
int randIndex = rand() % _set.size();
int num = _set[randIndex];
_set.erase(_set.begin() + randIndex);
return num;
}
This chooses a random int from a provided set of numbers, and removes that choice from the set so that it can't be picked again.
Used like so:
std::vector<int> mySet {0,1,2,3,4,5,6};
std::cout<<randomFromSet(mySet)<<'\n;
#include <random>
#include <vector>
#include <numeric>
#include <iostream>
using std::cout;
using std::endl;
int main() {
const int sz = 7;
std::vector<int> nums(sz);
std::iota(std::begin(nums), std::end(nums), 0);
std::default_random_engine re;
int i = 8;
while(--i > 0) {
auto my_set{ nums };
std::shuffle(my_set.begin(), my_set.end(), re);
for (auto x : my_set) {
cout << x << " ";
}
cout << endl;
}
}
Im new to c++ , can I add my answer too?
its c-style c++ sorry for that.but its easy to code and to understand at the same time.
#include <iostream> //std::cout
#include <ctime> //time() function
#include <cstdlib> //rand() and srand() functions
void rand_gen(unsigned int arr[],unsigned int sizeofarray)
{
srand((unsigned int)time(0);
for (unsigned int c = sizeofarray ; c > 0 ; c--)
{
unsigned int r = rand()%sizeofarray;
if (arr[r] != 404)
{
std::cout<<"Try No."<<(sizeofarray+1)-c<<" : "<<arr[r]<<"\n";
arr[r] = 404;
} else { c++; }
}
}
int main()
{
unsigned int n[7]={0,1,2,3,4,5,6};
rand_gen(n,7);
std::cin.get();
return 0;
}
I am working on creating a simulation of a test that will
1. randomize multiple choice answers
2. display the choices from a) b) c) d)
I have both codes done separately however can I use on for-loop to go about displaying this? Is this the best way to do this? All help is appreciated thank you!
#include <iostream>
#include <ctime>
#include <cstdlib>
using namespace std;
int main (){
const int TEST_SIZE = 13;
srand(time(0));
string animals[TEST_SIZE] = {"dog","cat","fish","elephant","rhinoceros","cheetah","tiger","lion","zebra","giraffes","alligators","sloths","kangaroos" };
for (int i = 0; i < TEST_SIZE; i++){
//generate random index number (0,1,2,3,4,5...)
int index = rand() % FACE_SIZE;
//swap animals[i] with animals[index]
string temp = animals[i];
animals[i] = animals[index];
animals[index] = temp;
}
//loop through array and print values
for (int i = 0; i < 7; i++){
cout << animals[i] << " ";
}
}
//separate code for part 2: choices from a-g
#include <iostream>
#include <string>
using namespace std;
int main()
{
const int CHOICE_SIZE = 7;
string choices[] = { "a)", "b)","c)","d)","e)","f)","g)" };
for (int i = 0; i < CHOICE_SIZE; i++) {
cout << choices[i] << " ";
}
}
You can iterate over both arrays and stop when smaller will ends
#include <iostream>
#include <ctime>
#include <cstdlib>
using namespace std;
int main (){
const int TEST_SIZE = 13;
srand(time(0));
string animals[TEST_SIZE] = {"dog","cat","fish","elephant","rhinoceros","cheetah","tiger","lion","zebra","giraffes","alligators","sloths","kangaroos" };
for (int i = 0; i < TEST_SIZE; i++){
//generate random index number (0,1,2,3,4,5...)
int index = rand() % FACE_SIZE; // maybe here should be TEST_SIZE?
//swap animals[i] with animals[index]
string temp = animals[i];
animals[i] = animals[index];
animals[index] = temp;
}
//loop through array and print values
for (int i = 0; i < 7; i++){
cout << animals[i] << " ";
}
const int CHOICE_SIZE = 7;
string choices[] = { "a)", "b)","c)","d)","e)","f)","g)" };
for (int i = 0; i < CHOICE_SIZE && i < TEST_SIZE; i++) {
cout << choices[i] << " " << animals[i] << ", ";
}
}
Also, consider that if you want to use fixed-size array, you can use std::array:
#include <array>
std::array<string, TEST_SIZE> animals = {...};
And for shuffling you can use std::shuffle from 'algorithm' header .
I need to generate random non repeating number array in C++, in this part of code I generate random numbers using, srand function, but some of the numbers are repeating. The main task is to generate random numbers for lottery ticket, so I need to generate numbers until golden number which is marked as int golden.
#include <cstdlib>
#include <ctime>
#include <iostream>
using namespace std;
int main()
{
int golden = 31;
int i = 0;
int array[35];
srand((unsigned)time(0));
while(i != golden){
array[i] = (rand()%75)+1;
cout << array[i] << endl;
i++;
}
}
One strategy is to populate an array with numbers from 1 to 75, and then use std::random_shuffle() on it. You can then read the numbers from the array until you hit the golden number.
I had a similar task and used two functions to solve the problem of repeating numbers.
#include <iostream>
#include <ctime>
using namespace std;
void generateRandom(int array[], int length);
bool findVal(int array[], int size, int value);
int main() {
int arraySize = 10;
int array[arraySize];
generateRandom(array, arraySize);
for (auto i : array) {
cout << i << " ";
}
return 0;
}
void generateRandom(int array[], int length) {
srand((int) time(nullptr));
int temp;
for (int i = 0; i < length; ++i) {
temp = rand() % 20 + 1;
if (findVal(array, i, temp)) {
i--;
continue;
} else {
array[i] = temp;
}
}
}
bool findVal(int *array, int size, int value) {
for (int i = 0; i < size; ++i) {
if (array[i] == value) {
return true;
}
}
return false;
}
Within the generateRandom function, you can switch the 20 and 1 used in the for loop with your preferred upper and lower limits respectively.