C Language---Advanced pointer 2 (struct pointer, array as function parameter)

First, the structural body pointer

1. What is a struct pointer? Pointer to struct-body variable

struct: typedef struct stu{

Char name[20];

char sex;

int age;

}student;

Student stu1 = {"Zhangsan", ' m ', 23};

Student *p = &stu1;

p is a struct pointer that holds the address of the first member of a struct variable.

Student stu2 ={"Lisi", ' m ', 26};

*p = STU2;

(*p). Sex = ' f '; modifying struct variables (usually with p->sex = ' f ')

2. Structure array and pointer relationship

Student Stus[5] = {

{"Zhangsan", ' m ', 23},

{"Lisi", ' F ', 24},

{"Wangwu", ' m ', 28},

{"Zhangda", ' m ', 17},

{"Qianer", ' F ', 22}

}

Student *p1 = &stus[3];p The first address to stu[0], the length of the address is Student type

Student *p2 = stus; The array name represents the first address of the array, which is the address of the first element (Stu[0]) of the array.

Change the gender of Zhaoda to female, p1->sex = ' f ';

3. struct student{

Char *name;

}

member defined as Char name[20], difference?

Char name[20] occupies 20 bytes and is actually in memory.

Char *name occupies 8 bytes pointing to the name of the constant area, which does not exist itself, is an address and is a pointer.

4. When an array is used as a function parameter, the first address of the array is actually passed to the function.

Statement: Printmaxvalueofarray (int a[100]);

System default: Printmaxvalueofarray (int *a);

That is, regardless of the definition of a[200] or a[100], the system defaults to the first address of array A is a.

Note: It is either defined as int a[], or it is defined as an int *a, and two must be followed by an int count;

Main function:Printmaxvalueofarray (A,sizeof (a)/sizeof (a[0]));

5. Pointers can be used as arrays

void PrintArray (int *arr,int count);

void PrintArray (int *arr,int count) {

for (int i = o; i < count; i++) {

Print ("%d", arr[i]);

}

}

Pointers can be used as arrays, and arrays can also be used as pointers

Note: The array acts as a function parameter, and the formal parameter represents only the first element address of the array, the number of incoming

6. Strings and pointers

A string is actually a character array.

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Pointer + + moves one type so long distance at a time

C Language---Advanced pointer 2 (struct pointer, array as function parameter)