Help Using Pointers

I have listed my code. My numbers are being read but the product and sum are not displaying the correct answer. What am I missing? Any suggestions?

Code:

---

#include <stdio.h>

void sum_product(int* x, int* y);

void main()
{
        int num1;
        int num2;
        double product;
        int sum;
       
       


        printf("Enter two integers: ");
        scanf("%d%d", &num1, &num2);
       
        printf("The # is %d and %d\n", num1, num2);
       
       
        sum_product(&num1, &num2);

        printf("The sum is %d\n", &sum);
        printf("The product is %d\n", &product);


}


void sum_product(int *x, int *y)
{               

        double *product =  (*x) * (*y);
        int *sum = *x+*y;
       
       

       
}

---

You probably want to pass sum and product to sum_product.

[edit]Don't use void main -- see the FAQ if you are tempted to ask why.

Code:

---

        printf("The sum is %d\n", &sum);
        printf("The product is %g\n", &product);

---

Remove the &'s, and use a floating-point format specifier for product.

I do not understand what you mean. I am new to using pointers. In this program I have to find the sum and product of two integers inputed by the user using the function prototype: void sum_product(int *x, int *y); I do not understand what I am doing wrong.

Code:

---

void sum_product(int *x, int *y)
{               
        double *product =  (*x) * (*y);
        int *sum = *x+*y;
}

---

Here product and sum are pointers. They do not point to any valid memory that you can write to. Yet you go ahead and calculate a value and trample right over the memory that you can't write to by writing to it.

I would expect the function to be defined like this.

Code:

---

void sum_product(int *x, int *y, double *product, int *sum)

---

[edit]If you need to keep your prototype as is, you'll have to do your calculations and printing from within sum_product.

Do you have to use pointers for this problem or you can do it any other way? I really dont see why you would want to use pointers for such a simple problem. You can have 2 functions instead, 1 for the sum and 1 for the product to make your job easier and the program more readable. Here is a tip for you

Code:

---

#include <stdio.h>

int product(int num1, int num2);

int main()
{
        int num1;
        int num2;


        printf("Enter two integers: ");
        scanf("%d%d", &num1, &num2);
       
        printf("The # is %d and %d\n", num1, num2);
        printf("The product is %d\n",product(num1,num2));

}


int product(int num1, int num2)
{               
        return (num1 * num2);       
}

---

I agree, this would be much simpler without the pointers but I have to use them

In that case you might want to read this http://faq.cprogramming.com/cgi-bin/...&id=1043284351 hope it helps you.

I changed my code based on the prototype suggested. but results are still not right. My results are displaying sum = 1245036 and product = 1245040

Code:

Code:

---

#include <stdio.h>

void sum_product(int *x, int *y, double *product, int *sum)
{               

        *product =  (*x) * (*y);
        *sum = *x+*y;
}


main()
{
        int num1;
        int num2;
        double product;
        int sum;
       
        printf("Enter two integers: ");
        scanf("%d%d", &num1, &num2);
       
        printf("The # are %d and %d\n", num1, num2);
       
       
        sum_product(&num1, &num2, &product, &sum);

        printf("The sum is %d\n", &sum);
        printf("The product is %d\n", &product);


}

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Been there already.

Quote:

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Originally Posted by Dave_Sinkula

Code:

---

        printf("The sum is %d\n", &sum);
        printf("The product is %g\n", &product);

---

Remove the &'s, and use a floating-point format specifier for product.

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Thank you so much! Everything is working fine. Can you please tell me where I can find more information on the %g. I have never used that before

http://www.rt.com/man/printf.3.html

[edit]FAQ > How do I... (Level 1) > Format output using printf() (C)