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Since this space is contiguous, that is, created from sequential memory locations, we have essentially created an array of 5 integers.We will examine this further, but we need to first figure out how to access each integer in this space by doing arithmetic on pointers. When a pointer is declared, the data type it points to is recorded.These two ideas are so very close that C treats them the same.
As with other variables, if we try to assign values from incompatible types, errors will result.
We have said that a pointer contains an address into memory.
Pointers are a way to get closer to memory and to manipulate the contents of memory directly.
In this chapter, we will discuss pointers and how pointers are used to work with memory.
We will discuss how memory can be dynamically allocated and manipulated using pointers.
And we will see that arrays and pointer are very closely connected.For example, if a pointer contains the address of an integer, then adding one to that pointer means skipping 4 bytes to point to the next integer.If the data type is larger, the increment will increase the pointer the correct amount of bytes. This is especially useful when a pointer points to the beginning of an allocated area in memory.If addresses are just numbers, then we can do computations with them.Indeed, we can do pointer arithmetic in an intuitive fashion.We know variables in C are abstractions of memory, holding a value.That value is , defined by a data type definition in the variable declaration. A pointer is a variable whose value is an address, typed by its declaration. That fact might seem intuitive for other data types, but it's hard to remember for pointers.Pointers "point to" a variable (memory) with a typed value by referencing that variable, not by name, but by address. In the above examples, the variables are meant to contain the address of other variables, but they have not been initialized yet.Declaration Notation At first glance, the notation used to declare pointers might seem wrong.Let's say that we have code that just allocated space in memory for 20 integers: from it.It is our only way to access all the long integers in the allocated space and we must be careful to work with the pointer so it accurately points to the elements we need.