Question

Sorry if this is a silly question 🙂

Background

I have legacy code that looks like this:

struct {
int field1;
int field2;
int field3;
int field4;
... many many fields
} myStruct;


while (something) {
initialzationFunction(&myStruct);

// ...change fields of myStruct and do stuff.
}

Each iteration of the while loop needs that myStruct will be initialized to something, lets say zero.
initialzationFunction initializes all the fields of myStruct to zero.

The question

Is it good to keep initialzationFunction inside the while loop,
or is it better to call it once before the loop, and let the programmers initialize what they need “by hand” if they happen to change this code.

edit: Unfortunately myStruct is a global variable, so making it an automatic variable isn’t an option, unless I want to pass it as a parameter to tons of legacy functions that use it.

What I think

• just calling initialzationFunction() will prevent bugs in case someone modifies the code and forgets to later initialize myStruct.
• It might be more informative to see what specific fields are initialized.
• If only a few fields are modified later in the while loop, calling initialzationFunction() that inits all of the fields is redundant.

What would you do?

Answer 1

Since the struct fields are changed inside the while loop, it makes sense to initialize it during each iteration for whatever the purpose of processing done in the loop.

I would say it’s fine to to re-initialize few fields even if there were not modified in the loop. But keeping track of which fields were modified and excluding those fields
when initializing duing the next iteration would be a hassle which you can do without.

An alternative would be to use a temporary strucy variable with the initialization values and simply assign it at the start of every iteration.