8.2 Pointer variables as function parameters.mp4慕课视频播放-C Programming-MOOC慕课视频教程-柠檬大学

大家好，我是云南大学信息学院丁海燕老师

欢迎走进C语言程序设计课堂

今天我们讲解指针变量作为函数参数

函数的参数不仅可以是整型、浮点型、字符型等数据

还可以是指针类型。它的作用是将一个变量的地址

传送到另一个函数中。下面通过一个例子来说明

下面来看例8.3 对输入的两个整数按大小顺序输出

现用函数处理，而且用指针类型的数据作函数参数

解题思路：定义一个函数swap

将指向两个整型变量的指针变量作为实参

传递给swap函数的形参指针变量

在函数中通过指针实现交换两个变量的值

程序如下：

{ void swap(int *p1,int *p2);声明函数swap

int a,b;

int *pointer_1, *pointer_2;定义两个int *型的指针变量

用scanf(“%d,%d”,&a,&b); /输入两个整数，如5，9

使pointer_1指向a

使pointer_2指向b

if (a

输出结果

swap函数定义如下：

void swap(int *p1,int *p2)

{ int temp;

temp=*p1;

*p1=*p2;

*p2=temp; //交换目标变量，即a和b的值}

本例采取的方法是交换*p1和*p2

即交换a和b的值，情况如图所示

输入a,b为5，9，输出max=9,min=5

执行swap函数后，变量a,b的值交换了

这个改变不是通过将形参值传回实参来实现的

swap函数如果写成下面这样，则是错误的。

{ int *temp;

*temp=*p1;

*p1=*p2;

*p2=*temp;}

如果将swap函数改为下面这样

形参x,y发生了交换，但实参a,b无法交换

void swap(int x,int y)

{ int temp;

temp=x; x=y; y=temp;

因此，如果想通过函数调用得到ｎ个要改变的值：

1 在主调函数中设ｎ个变量，用ｎ个指针变量指向它们

② 设计一个函数，有n个指针形参

在这个函数中改变这ｎ个形参的值

③ 在主调函数中调用这个函数

在调用时将这n个指针变量作实参

将它们的地址传给该函数的形参

④ 在执行该函数的过程中，通过形参指针变量

改变它们所指向的ｎ个变量的值

⑤主调函数中就可以使用这些改变了值的变量

下面来看例8.4 对输入的两个整数按大小顺序输出

解题思路：尝试调用swap函数来实现题目要求

在函数中改变形参(指针变量)的值

希望能由此改变实参(指针变量)的值

注意：不能企图通过改变指针形参的值而使指针实参的值改变

请看下面的程序

{void swap(int *p1,int *p2);

用scanf("%d,%d",&a,&b); //输入5,9

pointer_1=&a; pointer_2=&b;

if (a

输出max=5,min=9

swap定义如下

{ int *p;

p=p1; p1=p2; p2=p; 这个语句错误，只交换了形参指向

并没有交换实参a和b

注意：函数的调用可以（而且只可以）得到

一个返回值（即函数值），而使用指针变量作参数

可以得到多个变化了的值

如果不用指针变量是难以做到这一点的

要善于利用指针法。

下面来看例8.5 输入3个整数a,b,c

要求按从大到小的顺序将它们输出，用函数实现

解题思路：采用例1的方法在函数中改变这3个变量的值

用swap函数交换两个变量的值

用exchange函数改变这3个变量的值

主函数如下：

void exchange(int *q1, int *q2, int *q3)

声明函数exchange

scanf输入3个整数

p1=&a; p2=&b; p3=&c;

exchange(p1,p2,p3); 调用函数exchange

输出a，b，c的值

注意：exchange函数调用结束后不会改变指针的指向

下面是exchange和swap函数的定义

void exchange(int *q1, int *q2, int *q3)

定义将3个变量的值交换的函数

声明函数swap

if(*q1<*q2) swap(q1,q2);如果a

if(*q1<*q3) swap(q1,q3);如果a

if(*q2<*q3) swap(q2,q3);如果b

void swap(int *pt1, int *pt2)定义交换两个变量的值的函数

{ int temp;

temp=*pt1; *pt1=*pt2; *pt2=temp;

这是交换指针指向的变量值

运行程序，输入20，-54，67，输出降序排列67，20，-54

好了，同学们

指针变量作为函数参数我们就学习到这儿，下节课再见!

C Programming课程列表：

Chapter 1 Introduction

-1.1 The development and characteristics of C language

--1.The development and characteristics of C language .mp4

--1.1 Self test questions

-1.2 A simple C Language program

--1.2 A simple C Language program.mp4

--Discussion unit

--【Source program】 Example 1.1 output a line of text Hello, world! "

--【Source program】 Example 1.2 program composed of multiple functions, find the larger of two integers

--1.2 Self test questions

-1.3 Program, Programming Language and C Program Running Steps

--1.3 Program, Programming Language and C Program Running Steps.mp4

--Discussion unit

--Running steps of C source program in CodeBlocks

--1.3 Self test questions

-Course references

-chapter 1 Self-Test

Chapter 2 Algorithm

-2.1 The Concept and Description of Algorithms

--2.1 The Concept and Description of Algorithms.mp4

--Discussion unit

--2.1 Self test questions

-2.2 Examples of Simple Algorithms, Computational Thinking and Structured Programming

--2.2 Examples of Simple Algorithms, Computational Thinking and Structured Programming.mp4

--Discussion unit

--2.2 Self test questions

-Chapter 2 Self test questions

Chapter 3 Programming in C

-3.1 Simple Structure and Identifier of C Language Program

--3.1 Simple Structure and Identifier of C Language Program.mp4

--【Source program】 Example 3.1 input two integers and output the sum of two numbers.

--【Source program】 Example 3.2 input two integers and output the average value.

--【Source program】 Example 3.3 output the value of the character variable.

--3.1 Self test questions

-3.2 Constants, Variables and Assignments

--3.2 Constants, Variables and Assignments.mp4

--Discussion unit

--3.2 Self test questions

-3.3 Arithmetic, assignment, increment and decrement operators

--3.3 Arithmetic, assignment, increment and decrement operators.mp4

--3.3 Self test questions

-3.4 Conditions, commas, addresses, byte operators, and mixed operations among various numerical data

--3.4 Conditions, commas, addresses, byte operators, and mixed operations among various numerical data

--【Source program】 example of sizeof

--3.4 Self test questions

-3.5 Input and Output Examples and Character Input and Output

--3.5 Input and Output Examples and Character Input and Output.mp4

--【Source program】 Example. Find the root of quadratic equation of one variable.

--【Source program】 Example 1. Successively output three characters of BOY.

--【Source program】Example 2. Input 3 characters of BOY from the keyboard and output them to the screen

--3.5 Self test questions

-3.6 Formatted output printf function

--3.6 Formatted output printf function.mp4

--【Source program】 Example 3.4 output of integer data.

--【Source program】 Example 3.5 real data output.

--【Source program】 Example 3.6 character data output.

--【Source program】 Example 3.7 uses %s to output a string.

--3.6 Self test questions

-3.7 Formatted input scanf function

--3.7 Formatted input scanf function.mp4

--Discussion unit

--【Source program】 Example 3.8 Input and output integer data

--【Source program】Example 3.9 Input and output single precision and double precision real data.

--【Source program】Example 3.10 input and output character data.

--【Source program】Example 3.11 input and output string.

--3.7 Self test questions

-3.8 Basic Data Types of C Language

--3.8 Basic Data Types of C Language.mp4

--3.8 Self test questions

-Chapter 3 Self test questions

-Operator and expression self test questions

Chapter 4 Selection Structure

-4.1 Relational operators, logical operators, and if statements

--4.1 Relational operators, logical operators, and if statements.mp4

--Discussion unit

--【source example】Example 4.1 Find the root of the quadratic equation of one variable.

--【Source program】Example 4.2 Input two real numbers and output them from small to large.

--4.1 Self test questions

-4.2 Switch Statement

--4.2 Switch Statement .mp4

--Discussion unit

--【Source program】Example 4.3 uses switch statement to implement simple menu program

--【Source program】Example 4.4 converts centesimal score into the corresponding grade system score.

--4.2 Self test questions

-4.3 Examples of Selection Structural Programs

--4.3 Examples of Selection Structural Programs.mp4

--【Source program】 Example 4.5 determines whether a year is a leap year.

--【Source program】 Example 4.6 find the solution of quadratic equation of one variable.

--【Source program】Example 4.7 calculate the transportation cost for the user.

--4.3 Self test questions

-Chapter 4 Self test questions

Chapter 5 Loop Structure

-5.1 While and Do-While Statement

--5.1 While and Do…while statement.mp4

--Discussion unit

--【Source program】example 5.1 Use while statement to find 1 + 2 + 3 + +100

--【Source program】example 5.2 using do while statement to find 1 + 2 + 3 + +100

--5.1 Self test questions

-5.2 For Statement

--5.2 for statement.mp4

--【Source program】example 5.3 Use for loop to find 1 + 2 + 3 +100

--5.2 Self test questions

-5.3 Change the State of Loop Execution and Nested Loop

--5.3 Change the state of loop execution and nested loop .mp4

--【Source program】example 5.4 collecting charity donations

--【Source program】example 5.5 output a number between 100 and 200 that cannot be divided by 3.

--【Source program】multiplication table

--【Source program】example 5.6 Output the following 4*5 matrix.

--5.3 Self test questions

-5.4 Loop Structure Program example 1

--5.4 Loop structure program example 1.mp4

--【Source program】example 1

--【Source program】example 2

--【Source program】example 3

--【Source program】 Example 4

--5.4 Self test questions

-5.5 Loop Structure Program example 2

--5.5 Loop structure program example 2.mp4

--【Source program】example 5. Output the following figure.

--【Source program】example6. The problem of 100 chickens and 100 coins

--【Source program】example 7. Find the approximate value of PI

--5.5 Self test questions

-Chapter 5 Self test questions

Chapter 6 Batch Data Processing with Array

-6.1 Definition, Reference and Initialization of One-Dimensional Arrays

--6.1 Definition, Reference of One-Dimensional Arrays.mp4

--Discussion unit

--6.1 Self test questions

-6.2 One-Dimensional Array Programming

--6.2 One-Dimensional Array Programming.mp4

--【Source program】example 1. Fibonacci sequence

--【Source program】example 2. Find the maximum value and the minimum value.

--【Source program】example 3 exchanging array elements in reverse order.

--【Source program】example 4. Bubble sorting.

--6.2 Self test questions

-6.3 Definition, Reference and Initialization of Two-Dimensional Arrays

--6.3 Definition, Reference of Two-Dimensional Arrays.mp4

--6.3 Self test questions

-6.4 Two-Dimensional Array Programming

--6.4 Two-Dimensional Array Programming.mp4

--【Source program】example 1. Get the average score of each subject.

--【Source program】Example 2. The elements of row and column of a 2D array are interchanged

--6.4 Self test questions

-6.5 Definition, initialization and input and output of character arrays

--6.5 Definition, initialization and input and output of character arrays .mp4

--Discussion unit

--【Source program】Example 6.6 Output a known string.

--【Source program】Example 6.7 Output a diamond.

--【Source program】Example 6.10 Sorting of strings.

--6.5 Self test questions

-6.6 String Processing Function

--6.6 String Processing Function.mp4

--6.6 Self test questions

-6.7 Character Array Programming

--6.7 Character Array Programming.mp4

--6.7 Self test questions

-Chapter 6 Self test questions

Chapter 7 Modular Programming with Functions

-7.1 Function Concept and How to Define and Call Functions

--7.1 Function Concept and How to Define and Call Functions.mp4

--【Source program】Example 7.1

--7.1 Self test questions

-7.2 Data Transfer in Function Call, Call Procedure and Function Return Value

--7.2 Data Transfer in Function Call, Call Procedure and Function Return Value.mp4

--Discussion unit

--【Source program】Example 7.2

--7.2 Self test questions

-7.3 Declarations of called functions and nested calls to functions

--7.3 Declarations of called functions and nested calls to functions .mp4

--【Source program】Example 7.4 use a function to find the sum of t

--7.3 Self test questions

-7.4 Recursive call to function

--7.4 Recursive call to function.mp4

--【Source program】Example 7.6. How old is the fifth student?

--【Source program】Example 7.7 Use recursion method to find n!

--7.4 Self test questions

-7.5 Array as function parameter (1)

--7.5 Array as function parameter (1).mp4

--Discussion unit

--【Source program】Example 7.10

--7.5 Self test questions

-7.6 Array as function parameter (2)

--7.6 Array as function parameter (2).mp4

--【Source program】Selection sorting.

--【Source program】Example 7.13 find the maximum of a 3×4 matrix.

--7.6 Self test questions

-7.7 Local and global variables, internal and external functions

--7.7 Local and global variables, internal and external functions.mp4

--【Source program】Example 7.14

--7.7 Self test questions

-7.8 The Survival Period of Variables and the Storage Mode of Local Variables

--7.8 The Survival Period of Variables and the Storage Mode of Local Variables.mp4

--【Source program】Example 7.17

--7.8 Self test questions

-7.9 Storage Categories of Global Variables

--7.9 Storage Categories of Global Variables.mp4

--7.9 Self test questions

-Chapter 7 Self test questions

Chapter 8 Pointer

-8.1 Pointer Concept, Definition and Reference of Pointer Variables

--8.1 Pointer Concept, Definition and Reference of Pointer Variables.mp4

--【Source program】Example 8.1

--8.1 Self test questions

--Discussion unit

-8.2 Pointer variables as function parameters

--8.2 Pointer variables as function parameters.mp4

--Discussion unit

--【Source program】Example 8.3. Exchange two data with function call.

--8.2 Self test questions

-8.3 Pointer of array element, operation of pointer and reference of array element by pointer

--8.3 Pointer of array element, operation of pointer and reference of array element by pointer.mp4

--【Source program】Point to array elements with pointer variables.

--8.3 Self test questions

-8.4 Using Array Name as Function Parameter

--8.4 Using Array Name as Function Parameter.mp4

--【Source program】Store array elements in reverse order.

--8.4 Self test questions

-8.5 Reference to multidimensional arrays by pointers

--8.5 Reference to multidimensional arrays by pointers.mp4

--【Source program】Pointer variable pointing to one-dimensional array.

--8.5 Self test questions

-8.6 Referencing strings through pointers

--8.6 Referencing strings through pointers.mp4

--【Source program】Reference string by pointer.

--8.6 Self test questions

-8.7 Character pointer as function parameter

--8.7 Character pointer as function parameter.mp4

--【Source program】Character pointer as function parameter.

--8.7 Self test questions

-8.8 Pointer pointing to function

--8.8 Pointer pointing to function.mp4

--【Source program】Pointer variable pointing to the function.

--8.8 Self test questions

-8.9 Functions that return pointer values

--8.9 Functions that return pointer values.mp4

--【Source program】Intercept substring.

--8.9 Self test questions

-8.10 Pointer arrays and multiple pointers

--8.10 Pointer arrays and multiple pointers.mp4

--【Source program】Sorting of strings.

--8.10 Self test questions

-8.11 Dynamic memory allocation and pointer variables pointing to it

--8.11 Dynamic memory allocation and pointer variables pointing to it.mp4

--Discussion unit

--【Source program】Dynamic memory allocation.

--8.11 Self test questions

-Chapter 8 Self test questions

Chapter 9 Structure

-9.1 Define and use structural variables

--9.1 Define and use structural variables.mp4

--【Source program】Structure variable

--9.1 Self test questions

-9.2 Using structure arrays

--9.2 Using structure arrays.mp4

--Discussion unit

--【Source program】Structure array

--9.2 Self test questions

-9.3 Structure pointer

--9.3 Structure pointer.mp4

--【Source program】Structure pointer

--9.3 Self test questions

-Chapter 9 Self test questions

CodeBlocks Baidu online disk download

-CodeBlocks Baidu online disk download address

Final Exam

-Final Exam

--final exam

8.2 Pointer variables as function parameters.mp4在线视频

8.2 Pointer variables as function parameters.mp4课程教案、知识点、字幕

C Programming课程列表：

Chapter 1 Introduction

Chapter 2 Algorithm

Chapter 3 Programming in C

Chapter 4 Selection Structure

Chapter 5 Loop Structure

Chapter 6 Batch Data Processing with Array

Chapter 7 Modular Programming with Functions

Chapter 8 Pointer

Chapter 9 Structure

CodeBlocks Baidu online disk download

Final Exam

8.2 Pointer variables as function parameters.mp4笔记与讨论

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