struct: Basics

struct: Compound Datatypes

So far we had …

• Scalar datatypes: int, float, …

• Pointers

• Now for some … design

Fantasy:

• Pointers give us power to do more

• How do we build more complex data structures?

  • Linked lists

  • Balanced trees

  • …

struct: How?

Short and to the point …

/* type declaration - no memory set aside */
struct point
{
    int x;
    int y;
};

/* set aside memory for two points */
struct point p1, p2;

• New type: struct point

• Used just the same as other types

Usage

Operations Initialization Copy … Assignment Parameter passing Return from function Member access

/* initialization */ struct point p = { 42, 7 }; /* member access */ p.x = 1; /* assignment */ p2 = p;

Nested Structures

Nesting Nesting is possible But: structures become large through nesting Call-by-value (and return) makes copies!

Memory Layout

Structures are laid out in flat memory Linear sequence of bytes Copy (assignment, parameter, return) of memory is made

struct rect { struct point p1; struct point p2; };

Recursive Structures?

struct xxx
{
    struct xxx x;
};

• That particular structure would be infinitely large

• ⟶ Compiler error

• ⟶ Pointers