CODEWITHSUNDEEP
cmallocstructure
AndrewGrant
AndrewGrant

Reputation: 808

Initializing Malloc'ed structure

I am trying to initalize a structure using braces, but i am really trying to initalize the structure that is pointed to by a pointer returned from a malloc call.

typedef struct foo{
    int x;
    int y;
} foo;

foo bar = {5,6};

I understand how to do that, but i need to do it in this context.

foo * bar = malloc(sizeof(foo));
*bar = {3,4};

Upvotes: 9

Views: 2618

Answers (2)

jpw
jpw

Reputation: 44871

(This was answered in comments, so making it a CW).

You need to cast the right-hand side of the assignment, like so:

*bar = (foo) {3,4};

As pointed out by @cremno in the comment, this isn't a cast but rather an assignment of a compound literal

The relevant section of the C99 standard is: 6.5.2.5 Compound literals which says:

A postfix expression that consists of a parenthesized type name followed by a brace enclosed list of initializers is a compound literal. It provides an unnamed object whose value is given by the initializer list

Upvotes: 9

Shreyas Chavan
Shreyas Chavan

Reputation: 1099

bar is a pointer that holds reference to the malloced foo struct

Use bar->x=3;bar->y=4

Upvotes: 1

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