C language 03

To understand the array, first recognize the "address" in memory

I. Address

1. The memory in the computer is the storage space in bytes. Each byte of memory has a unique number, which is called an address. Every program and data stored in memory has an address, that is, a function has its own memory address.

2. When a variable is defined, the system allocates a storage unit with a unique address to store the variable.

3. During the commissioning process, we take a print view of the variable's address:

Ten;  output address printf in 16 binary form ("16 binary:%x\n", &C);  output address printf in 10 binary form ("10 binary:%d", &c);           

Two. one-dimensional arrays

* The form of the definition is: type array name [number of elements]

int a[5];

[] inside is a fixed value, constant or constant expression, cannot be a variable, in most cases do not omit the number of elements (when the array is initialized as a function parameter and arrays)

When you define an array, the system allocates a contiguous amount of storage space by array type and number to store the array elements, such as int a[3], which occupies a contiguous 6 bytes of storage (in a 16-bit compiler environment, an int type occupies 2 bytes). Note that the array name represents the address of the entire array, which is the starting address of the array.

* Element Value list can be the initial value of all elements of an array, or it can be the initial value of an element in the preceding section

int a[4] = {5}; 

When an array is an integer, initialize an element with an indeterminate initial value, which defaults to 0, so the above a[2], a[3] are 0

* When assigning initial values to all array elements, you can omit the number of elements

int a[] = {7};

Indicates that the number of elements in array A is 3

* Array initialization can only be used for the definition of the array, after the definition can only one element of an element to assign a value

Two-dimensional array initialization, you can omit the number of rows, but you can not omit the number of columns.

Three. String

C language 03