8.7 Character pointer as function parameter.mp4慕课视频播放-C Programming-MOOC慕课视频教程-柠檬大学

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欢迎走进C语言程序设计课堂

今天我们讲解字符指针作函数参数。

字符指针可以作函数实参或形参

如果想把一个字符串从一个函数

“传递”到另一个函数，可以用地址传递的办法

即用字符数组名作参数，也可以用字符指针变量作参数

在被调用的函数中可以改变字符串的内容

在主调函数中可以引用改变后的字符串

下面来看例8.20 用函数调用实现字符串的复制

解题思路：定义一个函数copy_string用来

实现字符串复制的功能，在主函数中调用此函数

函数的形参和实参可以分别用

字符数组名或字符指针变量

分别编程，以供分析比较

(1) 用字符数组名作为函数参数

{ void copy_string(char from[],char to[]);声明函数

char a[]="I am a teacher.";定义a字符数组

定义b字符数组

输出ab字符串

copy_string(a,b);调用函数用字符数组名a,b作为函数实参

用%s输出a,b的字符串

copy_string函数定义如下：

void copy_string(char from[], char to[])形参为字符数组

{ int i=0;

while(from[i]!='\0')

{ to[i]=from[i];把from[i]的值赋给to[i]

i++;}

最后to[i]='\0';

即，当复制完全部有效字符后加字符串结束标志’\0’}

程序运行结果如图所示

(2)用字符型指针变量作实参

copy_string不变

在main函数中定义字符指针变量from和to

分别指向两个字符数组a,b

仅需要修改主函数代码

程序如下：

首先声明函数

定义字符数组a并初始化

定义字符数组b并初始化

char *from=a,*to=b;

from指向a数组首元素，to指向b数组首元素

输出a,b字符串

copy_string(from,to)调用函数实参为字符指针变量

输出ab字符串

(3)用字符指针变量作形参和实参

程序如下

对copy_string进行声明

char *a=“I am a teacher.”; a是char *型指针变量

定义b字符数组并初始化

char *p=b;使指针变量p指向b数组首元素

输出a串和b串

copy_string(a,p);

调用函数

实参为指针变量

输出改变后的a串和b串

copy_string函数的形参为字符指针变量，定义如下：

void copy_string(char *from, char *to)

{ for( ;*from!='\0'; from++,to++)

{ *to=*from; }

最后*to='\0';}

函数体有多种简化写法，请见主教材

用字符指针变量和字符数组都能

实现字符串的存储和运算

但二者是有区别的，下面进行一个比较

(1) 字符数组由若干个元素组成

每个元素中放一个字符

而字符指针变量中存放的是地址

（字符串第1个字符的地址）

决不是将字符串放到字符指针变量中。

(2) 赋值方式。可以对字符指针变量赋值

但不能对数组名赋值

例如char *a; a=”I love China!”; 正确

char str[14]; str[0]=’I’; 正确

char str[14]; str=”I love China!”; 错误

(3)初始化的含义

char *a=”I love China！”; 与

char *a; a=”I love China！”; 等价

char str[14]= ”I love China！”;

不等价于

char str[14];

str[]=”I love China！”;

这是企图把字符串赋给数组中各元素，是错误

(4) 存储单元的内容

编译时为字符数组分配若干存储单元

以存放各元素的值，而对字符指针变量

只分配一个存储单元(VC++为指针变量分配4个字节)

如果定义了字符指针变量

应当及时把一个字符变量（或字符数组元素）

的地址赋给它，使它指向一个字符型数据

如果未对它赋地址值，它并未指向一个确定的对象

此时如果向该指针变量所指向的对象输入数据

可能会出现严重的后果

例如char *a; scanf(“%s”,a); 指针变量无指向，错误

以下代码正确

(5) 指针变量的值是可以改变的

而数组名代表一个固定的值(数组首元素的地址)

不能改变

下面来看例8.21 改变指针变量的值。

下面来看{ char *a="I love China!";

不能改为char a[]=“I love China!”;

a=a+7;

输出a的字符串

(6) 字符数组中各元素的值是可以改变的

但字符指针变量指向的字符串常量中

的内容是不可以被取代的。

char a[]=”House”,*b=” House”;

则a[2]=’r’; 正确

b[2]=’r’; 错

(7) 引用数组元数

对字符数组可以用下标法和地址法

引用数组元素如（a[5],*(a+5)）

如果字符指针变量p=a

则也可以用指针变量带下标的形式和地址法

引用数组元素如（p[5],*(p+5)）。

例如char *a=″I love China!″;

则a[5]的值是第6个字符，即字母’e’

(8) 用指针变量指向一个格式字符串

可以用它代替printf函数中的格式字符串

例如char *format;

format=”a=%d,b=%f ”;

printf(format,a,b);

相当于

printf(“a=%d,b=%f ”,a,b);

好了，同学们

字符指针作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

8.7 Character pointer as function parameter.mp4在线视频

8.7 Character pointer as function parameter.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

8.7 Character pointer as function parameter.mp4笔记与讨论

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