cfunctionpointers

Taking a structure pointer as a function's parameter

#include<stdio.h>

struct create
{
    int a;
    int b;
    int c;
    float total;
};

struct create Create[3];

float givename(struct create* storage[3]);

int main()
{
    for(int j = 0; j<4; ++j)
    {
        printf("Input a[%d]:", j+1);
        scanf("%d", &Create[j].a);
        printf("Input b[%d]:", j+1);
        scanf("%d", &Create[j].b);
        printf("Input c[%d]:", j+1);
        scanf("%d", &Create[j].c);
        float sum = givename(&Create);
        printf("%f", sum);
     }
}

float givename(struct create* storage[3])
{
    for(int i = 0; i<4; ++i)
    {
         storage[i]->total = storage[i]->a + storage[i]->b + storage[i]->c;
         return storage[i]->total;
     }
}

I wanted to take an input into an array of structures and then use it inside a function that has been called by reference.

What am I misunderstanding about the logic?

Solution

  • The function

    float givename(struct create* storage[3])

    takes an array of pointers to struct create, you are sending the address of an array of struct create. If you want an array of pointers to struct create, do it like this:

    struct create * array[3];
array[0] = & Create[0];
array[1] = & Create[1];
array[2] = & Create[2];

    Plus, this function stops during the first iteration, because of the return.

    Array's size is 3, you're looping 4 times.

    Your main needs a return value;

    If you wanted to pass the whole array to givename (an array of struct create, not pointers), you don't need to since Create is global;

    For each iteration in the first loop (3 after fixing), you iterate the whole array, I doubt this is what you wanted to do.

    The following version prompts to fill 3 struct create, computes the total for each (and stores it), and prints it. Is this what you wanted to do ?

    #include<stdio.h>
#include <stdlib.h>

struct create
{
    int a;
    int b;
    int c;
    float total;
};

struct create Create[3];

float givename(struct create * storage);

int main()
{
    for(int j = 0; j < 3; ++j)
    {
        printf("Input a[%d]:", j+1);
        scanf("%d", & Create[j].a);
        printf("Input b[%d]:", j+1);
        scanf("%d", & Create[j].b);
        printf("Input c[%d]:", j+1);
        scanf("%d", & Create[j].c);
        float sum = givename(& Create[j]);
        printf("%f\n", sum);
    }

    return EXIT_SUCCESS;
}

float givename(struct create * storage)
{
    storage->total = storage->a + storage->b + storage->c;
    return storage->total;
}

    echo 1 2 3 4 5 6 7 8 9 | yourProgram

>> Input a[1]:Input b[1]:Input c[1]:6.000000
>> Input a[2]:Input b[2]:Input c[2]:15.000000
>> Input a[3]:Input b[3]:Input c[3]:24.000000

    What you wanted to achieve is quite unclear, and the naming doesn't help, I recommend you to give better names:

    Consider compiling with -Wall -Wextra -Werror.