C Language Review 5

1. Two-dimensional array: is a special one-dimensional array

Full initialization:

1) int a[2][3]={{1,2,3},{2,3,4}};

2) Continuous assignment int a[2][3]={1,2,3,2,3,4};

3) The length of the first dimension can be omitted and the second dimension cannot be saved

int a[][3]={1,2,3,2,3,4};

Partial initialization

int a[2][3]={1,2,3};

Define a post-initialization first

2. Traversal of two-dimensional arrays

Dual cycle

3. Storage of two-d arrays, pre-column, continuous storage

The first address of a two-dimensional array = array name =&a[0]=&a[0][0]

Computes the total number of bytes consumed by the array name sizeof (a);

Number of bytes per line sizeof (a[0]);

How many columns are in each row: The number above/the number of bytes occupied by each element

Number of lines: sizeof (a)/sizeof (A[0])

4. String (double quotation marks, ending with a)

To save a string with a character array

1) Char str[4]={"Hello"};

2) Char str[4]= "Hello";

3) Char str[]= "Hello";

String output

Print ("%s", str);//str is the first address of a string

Print ("%s", &str[0]);//%s starts printing from the given address until the end of the

%s input, if the string has a space, then the character after the space cannot be received save

To calculate the length of a string:

1) Use strlen (str); function

2) Iterate through the array, encounter the end of the cycle, return the number

String handling functions

1) input/output function, including stdio.h

Puts output a string, puts (the first address of the character array);

Gets input a string, gets (character array name) using the get will give a warning that there is an out-of-bounds problem. You can receive spaces, but you cannot format the session output.

2) string connection function, including string.h

strcat (OLDSTR,NEWSTR);//Connect newstr to oldstr behind, oldstr to be large enough

strcpy (OLDSTR,NEWSTR);//cover oldstr,oldstr with NEWSTR to be large enough

strcmp (str1, str2);//compare str1 and str size, STR1>STR2 return greater than 0

Strlen (STR1);//Calculate the length of a string

5. Pointers: Address

Pointer variable: The variable that holds the pointer

Pointer variable definition: data type * pointer variable name or data type * pointer variable name

Initialization of pointer variables: int *p=&a;int *p=null;

Get the memory space pointed to by the pointer variable with *P

If the pointer variable definition is not initialized later, this pointer variable holds a garbage number, which is called a wild pointer

C Language Review 5