5.3 Change the state of loop execution and nested loop .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

今天我们讲解如何改变循环执行的状态

在循环中可以用break语句提前终止循环

在第4章的switch结构中

我们已经接触过break语句的使用

break语句可以使执行语句的流程跳出switch结构

继续执行switch选择结构下面的语句

同样的，break语句还可以用来从

循环结构体内跳出循环结构，提前结束循环

去执行循环结构下面的语句，break语句的格式

break;break专用于循环体和switch结构中

不能单独使用

利用break语句能够强迫终止

本层循环，转到后续语句执行

下面来看例5.4 在全系1000学生中，征集慈善募捐

当总数达到10万元时就结束，统计此时捐款的人数

以及平均每人捐款的数目

编程思路如下

循环次数不确定，但最多循环1000次

在循环体中累计捐款总数

用if语句检查是否达到10万元

如果达到就不再继续执行循环，终止累加

计算人均捐款数

变量amount，用来存放捐款数

变量total，用来存放累加后的总捐款数

变量aver，用来存放人均捐款数

定义符号常量SUM代表100000

程序如下：#include

#define SUM 100000

//指定符号常量SUM代表100000

int main()

{ float amount,aver,total;

int i; //定义相关变量

for (i=1,total=0;i<=1000;i++)

{ printf("please enter amount:");

scanf("%f",&amount); //输入金额

total= total+amount; //计算累加和

if (total>=SUM) break; }

aver=total / i ;

输出i和aver的值

i<=1000表示应该执行1000次

if (total>=SUM) break; 表示达到10万，提前结束循环

aver=total / i ; 这里的i表示实际捐款人数

程序运行结果如图所示

if (total>=SUM) break; 表示如果总计

超过SUM (10万元)，则退出循环

break只能用于循环语句和switch语句之中

而不能单独使用

下面介绍continue语句

有时并不希望终止整个循环的操作

而只希望提前结束本次循环，而接着

执行下次循环。这时可以用continue语句

continue功能：中断循环体的

本次执行（即跳过循环体中尚未执行的语句）

立即开始执行下一次循环。

while, do-while, for语句的

continue语句的流程图如下所示。

下面来看例5.5 要求输出100～200

之间的不能被3整除的数

编程思路：

对100到200之间的每一个整数进行检查

如果不能被3整除，输出，否则不输出

无论是否输出此数，都要接着检查下一个数(直到200为止)。

流程图如下：

n首先赋值为100，判断n<=20是否成立？

是，再判断n能被3整除吗？

当n能被3带整除时，流程跳过printf函数语句

结束本次循环,然后进行循环变量n的增值（n++）

只要n<=200,就会接着执行下一次循环

如果n不能被3整除，就不会执行continue语句

而执行printf函数语句，输出不能被3整除的整数

for语句如下：

for(n=100;n<=200;n++)

{ if (n%3==0) continue;printf("%d ",n);}

程序运行结果如图所示，输出100-200

之间不能被3整除的所有数

break语句和continue语句的区别在于

continue语句只结束本次循环

而不是终止整个循环的执行

break语句结束整个循环过程

不再判断执行循环的条件是否成立

循环还可以嵌套使用

如果循环语句的循环体内又包含了

另一条循环语句，则称为循环的嵌套

例如：以下程序输出9×9乘法表

main( )

{ int i, j;

for ( i=1; i<10; i++ ) //外循环控制行号

for ( j=1; j<=i; j++ ) //内循环控制列号

且列号<=行号

printf ((j==i)?"%4d ":"%4d",i*j); //输出每一行i*j的值}

程序运行结果如图所示。

while、do-while、for循环语句可以并列

也可以相互嵌套，但要层次清楚，不能出现交叉

多重循环程序执行时，外层循环每执行一次

内层循环都需要循环执行多次。

例如：for(a=1;a<=10;a++)

{ for (b=0;b<=5;b++)

外循环执行了10次，内循环执行6次

循环正常结束时，内循环执行了10×6=60次

下面来看例5.6 输出以下4*5的矩阵。

解题思路：

可以用循环的嵌套来处理此问题

用外循环来输出一行数据

用内循环来输出一列数据（行号乘以列号）

按矩阵的格式（每行五个数据）程序如下：

int main()

{ int i,j,n=0;

for (i=1;i<=4;i++)

for (j=1;j<=5;j++,n++) //用n累计数据的个数

{ if (n%5==0) printf (“ ”); //控制一行内输出5个数据

printf ("%d\t",i*j);}

本例中使用双重for循环输出多行多列的数据

for (i=1;i<=4;i++) 控制输出4行

for (j=1;j<=5;j++,n++) 控制每行中输出5个数据

i=1时，j由1变到5，i*j的值是1,2,3,4,5

i=2时，j也由1变到5，i*j的值是2,4,6,8,10

程序运行结果如下

假如在以上程序的基础上，作一些改动

在内循环体中增加一个if语句，if (i==3 && j==1) break;

实际输出结果如下，第3行空白

即不输出第3行的5个数据

如果把上面的break语句改为continue语句

即if (i==3 && j==1) continue; 输出如下：

好了，同学们，如何改变循环执行的状态

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

5.3 Change the state of loop execution and nested loop .mp4在线视频

5.3 Change the state of loop execution and nested loop .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

5.3 Change the state of loop execution and nested loop .mp4笔记与讨论

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