Initializers

So now you're probably wondering: "Hey TJ, so... how do we actually make an instance of a struct"? You may have noticed in the previous lesson all we did was define the struct type.

Unfortunately, there are a few different ways to initialize a struct, I'll give you an example of each using this struct:

struct City { char *name; int lat; int lon; };

Zero Initializer

int main() { struct City c = {0}; }

This sets all the fields to 0 values.

Positional Initializer

int main() { struct City c = {"San Francisco", 37, -122}; }

Designated Initializer

This is my (generally) preferred way to initialize a struct. Why?

• It's easier to read (has the field names)

• If the fields change, you don't have to worry about breaking the ordering

int main() { struct City c = { .name = "San Francisco", .lat = 37, .lon = -122 }; }

Remember, it's .name not name. If this trips you up, just remember it's .name and not name because that's how you access the field, e.g. c.name.

Accessing Fields

Accessing a field in a struct is done using the . operator. For example:

struct City c; c.lat = 41; // Set the latitude printf("Latitude: %d", c.lat); // Print the latitude

Note: There's another way to do this for pointers that we'll get to later.