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Pointer Pointers

• A pointer must always be of the same type as the variable it's pointing at.
• Declaring a pointer variable does not create the type of variable it points at. It creates a pointer variable.
• Though pointers are declared with an asterisk they are not always used with an asterisk.
• Pointers must be initialized before they can be used.
• Initialize a pointer by assigning it to a variable (of the same type).
• To assign a pointer to a variable, use an ampersand with the variable's name.

m_address = &memory;

• To assign a pointer to an array, do not use the ampersand:

s_address = string;

• To assign a pointer to an array element, use the ampersand:

element = &string[2];

• Without an asterisk, an initialized pointer holds a memory address.
• With an asterisk, an initialized pointer holds a value (the value of the variable the pointer points at).

Typical Pointer Setup and Use

First, create a pointer of the proper type:

float *f;

Second assign it to a variable's memory location:

f = &boat;

Finally, use the pointer:

printf("%.0f",*f);

• Without its asterisk, the pointer is a memory location.
• With its asterisk, the pointer equals the value at the memory location.
• Always use the same type of pointer as the variables it examines: floats for floats, ints for ints, and so on.
• Remember: Always initialize a pointer before you use it! Set the pointer equal to the address of some variable in memory.

Pointers, Parenthesis and Math

The ++ operator is used above, though any math operation can be substituted.

As a tip: Use parenthesis to isolate part of the pointer problem and the answer will always work out the way you intended.

Pointers and array brackets

Ugly ** notation