CODEWITHSUNDEEP
c++
logan_92
logan_92

Reputation: 117

returning an array address from function in c++ issue

i'm new to programming , this code gives me syntax error in line => int *result = apply_all(array1,5,array2,3) this is the error: expected primary-expression before '}' token|
i'm trying to write function called apply_all expects 2 arrays of integers and their sizes and dynamically allocates a new array of integers whose size is the product of 2 array sizes. the function should loop through the 2nd array and multiple each element accross each element of array 1 and store the product in newly created array. the function is returning a pointer of to the newly allocated array. also i wrote a function which is print to display the 1st & 2nd & newly array.

#include <iostream>

using namespace std;
//function prototype
int *apply_all(int *array1 ,int size1,int *array2,int size2);
void print(int *array,int size);



int main()
{
    int array1[] {1,2,3,4,5};
    int array2[] {10,20,30};

    cout << "Array 1:";
    print(array1,5);

    cout << "Array 2:";
    print(array2,3);

    int *result = apply_all(array1,5,array2,3);             
    cout << "Result : ";
    print(result,15);
    delete [] result;
    return 0;
}


int *apply_all(int *array1 ,int size1,int *array2,int size2)
{
        int *result {nullptr};
        result = new int[size1 * size2];   
        for (int i{0};i<size2;i++)          
            for(int j{0};j<size1;j++)          
                  *(result[i*5+j]) = *(array1[i])**(array2[j]);           
        return result;
}


void print(int *array,int size)
{
    for(auto num:array)
        cout << num << endl;
}

Upvotes: 0

Views: 152

Answers (2)

pleb_coder72
pleb_coder72

Reputation: 34

Since you are new, a simple work around would be creating an array with buffer space to store your results in and passing the pointer for this into apply_all. You could then write to this array which (being declared in main) should be very easy to access and cause few errors and use a c-string like ending to know when your results are over and to stop printing from the array (c-strings end with a value of 0 so that programs don't read unrelated memory). eg:

int buf[99];
apply_all(array_1, size1, array_2, size2, buf, size3);
for (int x = 0; buf[x] != end of buf var; x++;)
{
    print(buf[x])
}

and

apply_all()
{
    buf[start-end] = whatever you want;
    buf[end + 1] = some variable that won't appear in buffer; //max int size?
}

Upvotes: 1

cigien
cigien

Reputation: 60440

On this line:

*(result[i*5+j]) = *(array1[i])**(array2[j]);

since result[i*5+j] gives you an int, you are trying to dereference an int, which is not possible.

You just need to do:

result[i*5+j] = array1[i] * array2[j];

Also, in print, your range-for loop won't work with a pointer. You need to do:

for(int i = 0; i < size; ++i)
    cout << array[i] << endl;

Also, in apply_all, your loop bounds are incorrect. i needs to go till size1, and j needs to go to size2.

Here's a demo.

Upvotes: 2

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