Simple number generator with check function to avoid repeating

I am trying to write simple function to check if randomly generated value is already in array. I want to simply reach a number generator without repeating. Unluckly my code does not work. I mean it still generates me duplicated values. Could anyone tell me what I am doing wrong?

Checks if value exists in array:

bool valueExistsInArray(int* array, int value) {

if ((sizeof(array) / sizeof(*array)) <= 0)
return false;

int i = 0;

do {
if (array[i] == value)
return true;
i++;
} while (i < (sizeof(array) / sizeof(*array)));

return false;

}


Generating random values from specified range:

int generateRandomValue(int from, int to) {

return (std::rand() % (to-from+1)) + from;

}


Main function:

int main()
{
srand((unsigned int)time(NULL));

int array[10];
int i = 0;

do {

int value = generateRandomValue(1, 10);

if (!valueExistsInArray(array, value)) {
array[i] = value;
i++;
}

} while (i < (sizeof(array) / sizeof(*array)));

for (int i = 0; i < (sizeof(array) / sizeof(*array)); i++)
std::cout << "Index: " << i << " Value: " << array[i] << "n";


_getch();

return 0;

}


sizeof

std::vector

1 Answer
1

simple example how to do it using modern c++

#include <random>
#include <set>
#include <iostream>


int main()
{
const uint32_t minValue = 0;
const uint32_t maxValue = 1000000;

const size_t numValues = 100;

std::random_device rd;
std::uniform_int_distribution<int> dist(minValue, maxValue);

std::set<uint32_t> myNumbers;

while (myNumbers.size() < numValues)
{
myNumbers.insert(dist(rd));
}

for (const auto& val : myNumbers)
{
std::cout << val << "n";
}

return 0;
}


random_device and uniform distribution give you proper random values.

the "set" takes care of filtering duplicates.

std::shuffle

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