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14 Pointers

Among high-level languages, C is rather low level, close to the machine. This is mainly because it has explicit pointers. A pointer value is the numeric address of data in memory. The type of data to be found at that address is specified by the data type of the pointer itself. The unary operator ‘*’ gets the data that a pointer points to—this is called dereferencing the pointer.

C also allows pointers to functions, but since there are some differences in how they work, we treat them later. See Function Pointers.

• Address of Data  Using the “address-of” operator.
• Pointer Types  For each type, there is a pointer type.
• Pointer Declarations  Declaring variables with pointer types.
• Pointer Type Designators  Designators for pointer types.
• Pointer Dereference  Accessing what a pointer points at.
• Null Pointers  Pointers which do not point to any object.
• Invalid Dereference  Dereferencing null or invalid pointers.
• Void Pointers  Totally generic pointers, can cast to any.
• Pointer Comparison  Comparing memory address values.
• Pointer Arithmetic  Computing memory address values.
• Pointers and Arrays  Using pointer syntax instead of array syntax.
• Pointer Arithmetic Low Level  More about computing memory address values.
• Pointer Increment/Decrement  Incrementing and decrementing pointers.
• Pointer Arithmetic Drawbacks  A common pointer bug to watch out for.
• Pointer-Integer Conversion  Converting pointer types to integer types.
• Printing Pointers  Using printf for a pointer’s value.

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