CODEWITHSUNDEEP
carrayspointersrandom
Autumn Mills
Autumn Mills

Reputation: 7

My program is setting the first array element to the NUM_EL rather than a random number but the rest of the elements get randoms

#define NUM_EL 10

int randomArray1[NUM_EL];
int randomArray2[NUM_EL];
int sumArray[NUM_EL];

//Function Protocol
int IntializeArrayWithPointers(int, int, int);
void DisplayArrayDataWithPointers(int);
int AddTwoArraysWithPointers(int,int,int);

int main()
{   
    *randomArray1=IntializeArrayWithPointers(randomArray1, 0, 1);
    *randomArray2=IntializeArrayWithPointers(randomArray2, 10, 11);
    *sumArray=AddTwoArraysWithPointers(randomArray1,randomArray2,sumArray);
    DisplayArrayDataWithPointers(randomArray1);
    DisplayArrayDataWithPointers(randomArray2);
    DisplayArrayDataWithPointers(sumArray);
}


int IntializeArrayWithPointers(int pointer1[], int a, int b)
{
    int i;
    int* pa;
    pa= pointer1;

    for(i = 0; i < NUM_EL; i++)
    {
        pa[i] = rand()%(b-a+1)+a;
    }
}

void DisplayArrayDataWithPointers(int* p)
{
    int i;
    for(i = 0; i < NUM_EL; i++)
    {
        printf("arrayEL[%d] = %d at %p \n",i,p[i],&p[i]);
    }
    printf("\n");
}

int AddTwoArraysWithPointers(int a[],int b[],int c[])
{
    int i;
    int *pa;
    int *pb;
    int *pc;

    pa = a;
    pb = b;
    pc = c;
    for(i=0;i<NUM_EL;i++)
{
    *(pc +i)=*(pa +i)+*(pb +i);
}
}

The first element, when printing the array, always shows up as the value of NUM_EL. That happens even when I set it for rands between 0 and 1. The rest are random like they are supposed to be. The code works perfect except for the 1st element of each array including the sum array.

Upvotes: 0

Views: 80

Answers (2)

anshul garg
anshul garg

Reputation: 503

*randomArray1=IntializeArrayWithPointers(randomArray1, 0, 1);

This statement sets return value of function to first element of randomArray1.that why it's getting modified.

Remove the assignment and declare IntializeArrayWithPointers() with return type as void.

Upvotes: 0

interjay
interjay

Reputation: 110128

When you call the function, you do it like this:

*randomArray1=IntializeArrayWithPointers(randomArray1, 0, 1);

This will assign the return value of the function to the first element of randomArray1. Since you don't want this, you should remove the assignment.

In fact, the function doesn't even return a value so the behavior is undefined. You should declare the function as returning void.

Another issue is that the types in your function declarations don't match the types in the function definitions - always make sure they match, and pay attention to compiler warnings which would alert you to this.

Upvotes: 4

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