Why malloc memory in a function and free it outside is a bad idea?

Question

if this is a bad idea, how to allocate memory in the function?

Answer 1

It's not a bad idea if you just keep it consistent in your own style.

A good approach is to pass the allocated memory to the caller that can then free it when its done. Something like this:

void my_new(char **obj) {
    *obj = malloc(somesize);
}

and then call this from your function like this:

char *obj;

my_new(&obj);

/* work on obj */

free(obj)