CODEWITHSUNDEEP
cfunctionstruct
Gökhan Nas
Gökhan Nas

Reputation: 213

Return struct in a Function , Compile error

I am practicing on my C programming language skills and when i wrote this code compiler shows a bunch of error but i did not saw what is wrong with this. I am learnt this code on internet so hopefully you can help me :)

here is the code;

struct rect {

    int x1;
    int y1;
    int x2;
    int y2;
};



struct rect intersection(struct rect m, struct rect n) {
    struct rect intersection;
    if((n.x1 > m.x1) && (n.x1 < m.x2) && (n.y1 > m.y1 ) && (n.y1 < m.y2)){
                    rect intersection = {.x1=n.x1, .y1=n.y2, .x2=m.x2, .y2=m.y2};
                    return intersection;
                    }
    else if((m.x1 > n.x1) && (m.x1 < n.x2) && (m.y1 > n.y1 ) && (m.y1 < n.y2)){
                    rect intersection = {.x1=m.x1, .y1=m.y2, .x2=n.x2, .y2=n.y2};
                    return intersection;
                    }
    return NULL;
}

compile errors are at rect intersection = {.x1=m.x1, .y1=m.y2, .x2=n.x2, .y2=n.y2}; *error: field name not in record or union initializer

*error: incompatible types when returning type ‘int’ but ‘struct rect’ was expected
                     return intersection;
                     ^
*error: incompatible types when returning type ‘void *’ but ‘struct rect’ was expected
return NULL;
^

IF I MISS SOME INFO , PLEASE TELL ME

THANK YOU :)

Upvotes: 1

Views: 4860

Answers (3)

Jules Gagnon-Marchand
Jules Gagnon-Marchand

Reputation: 3781

The return type of your function is struct rect. NULL is a pointer or 0. You should either return a struct rect or change the return type of your function to struct rect* and a pointer to a heap malloc'd struct rect instead.

Upvotes: 5

Stack Exchange Broke The Law
Stack Exchange Broke The Law

Reputation: 58868

user2151287 suggested returning a pointer; but then you need something to point to, because

// this code is wrong
struct rect *some_function()
{
    struct rect x = {stuff};
    return &x;
}

is undefined behaviour - it has a chance of working anyway depending on how you use it, but eventually it won't work, and you'll be very confused.

You could return an empty rectangle (width and height = 0) instead:

struct rect x = {.x1=0, .y1=0, .x2=0, .y2=0};
return x;

By the way, your intersection function returns the wrong result in this case:

Upvotes: 1

sundq
sundq

Reputation: 763

 struct rect intersection = {.x1=n.x1, .y1=n.y2, .x2=m.x2, .y2=m.y2};//like this

 return NULL;//return intersection

My proposal is using pointer:the function return struct rect *,if this,you can return NULL when there is some error.

Upvotes: 2

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