07-c Language Process Control

First, Process Control

L Sequential structure: the default process structure. Each statement is executed in the written order.

L Select structure: Judge the given condition and decide which code to execute according to the result of judgment.

L Loop Structure: Executes a piece of code repeatedly when a given condition is true.

Second, choose the structure-IF1. Simple to use

L if (expression) statement 1;

u if (count>50) classes; Class

L if (expression) statement 1; Else Statement 2;

U f (count>50) classes; else no classes;

L if (expression) {}

u if (count>50) {class, Layout classroom;} else {}

Scope of the U {}

L If-else If-else

u if (a==0) else if (a>0) Else

U features: Only one parenthesis will be executed

L Compound Condition

U value range for class time (9~12 | | 14 ~17)

L Traps

u if (a!=0) {A is not 0;} else {A is 0;}

U if (a); {  }

u if (a=0)

u a = = 0;

U if (ten) int a = 9;

2. Exercises

1> Enter an integer day to represent the day of the week, according to the value of day to output the corresponding day of the week, such as day==1, the output "Monday"

2> Enter an integer, month, to represent the month, according to the month output corresponding to the season.

Spring: 3, 4, 5

Summer: 6, 7, 8

Autumn: 9, 10, 11

Winter: 12, 1, 2

3> Enter an integer score to represent the score, based on the score output level (A-E) (in two ways)

a:90~100

b:80~89

c:70~79

d:60~69

E:0~60

Third, choose the structure-switch1. Simple to use

L-switch (expression) {case numeric 1:break; ... default:break;}

l Example

int a = 10;

Switch (a) {

Case 0:

printf ("This is a 0");

Break

Case 5:

printf ("This is a 5");

Break

Case 10:

printf ("This is a 10");

Break

Default

printf ("nothing");

Break

}

L briefly describe the role of break

L Define variables in case

2. Comparison of IF and switch

L Many situations can be interchanged

L If used more, more flexible, switch can only a single value

3. Exercises

Use switch instead of if to implement the problem in if

IV. cyclic structure-while1. Simple to use

L Continuous printf ("push-ups") 20 times;

L while (expression) {}

L Continue: Output 5 times take a break.

L Use of break: Stop the loop at some time

2. Features

The loop body is executed only if the condition is established.

3. Exercises

1> prompts the user to enter a positive integer n to calculate the 1+2+3+...+n and

2> prompts the user to enter a positive integer n to calculate the 1-2+3-4+5-6+...+n and

4. Traps

while (condition);

V. Cyclic structure-do while

L Features: Must be executed once the body of the loop

L while and do While loop comparison

int i=0;
while (i<0) {
i++;
}

int i=0;
do{
i++;
} while (i<0);

Six, circular structure-for1. Simple and practical

L Running Process

L Initialization statements can be multiple sentences (place printf in the for parentheses)

2. For loop nesting

Friends List 1

Friends 1

Friends 2

Friends List 2

Friends 1

Friends 2

Friends List 3

Friends 1

Friends 2

3. Traps

1> dead loop for (;;);

2> scope of internal variables for the for loop body

3> Scope Confusion

for (int i = 0; i<5; i++) int a = 10;

4. While loop and for loop comparison

L can be interchangeable

L for loop variables can be recovered in time

5. Exercises

1> prompts the user to enter a positive integer n, if N5, outputs the following graph, the other n values, and so on

2> Output 99 Multiplication table

Seven, break and continue1. Break

L Use occasion: switch\ cycle Structure

L Break under Nested loops

2. Continue

L Application: Cyclic structure

L Continue under cyclic nesting

07-c Language Process Control