Kerala Plus Two Computer Science (DHSE): Structures and Pointers in C++

Structures and Pointers in C++

The exam tests whether you can model records with struct, access members correctly, and use pointers safely for indirection and dynamic data.

Structures

A struct groups variables of different types under one name. Each member has its own type.
Declare: struct Student { int roll; float marks; }; - the semicolon after } is mandatory.
Access with the dot operator: s1.roll = 12;. Structures can be nested and can form arrays.
Assignment between same-type structures copies all members.

Pointers

A pointer stores an address. int x = 5; int *p = &x; - & gives address, * dereferences.
For a structure pointer, use ->: p->roll is equivalent to (*p).roll.
Pointer arithmetic scales by the pointed-to type; p + 1 moves by sizeof(int) for an int*.

Worked example

struct Node { int data; Node *next; }; then Node n; Node *p = &n; p->data = 7; n.next = nullptr; Output of n.data is 7. Reasoning: p holds the address of n, so p->data writes into n.data. A self-referential next pointer is what makes linked structures possible.

Traps

Missing semicolon after a struct definition.
Dereferencing an uninitialised or deleted pointer (undefined behaviour).
Writing p.data when p is a pointer; use p->data.
Confusing *p++ with (*p)++; precedence changes the meaning.
Returning the address of a local variable, which becomes dangling.