Application practice of day13 for loop distinguish the application of traversing break continue

for loop

for( initialization , Boolean expression , to update ){ Code statements }

for( Defining variables , Boolean expression , expression ){ Output }

IDEA Shortcut 100.for It will pop up automatically

package com.ckw.blog.select;

public class demo_for {
    
    public static void main(String[] args) {
    
             // Initial value // conditional // iteration 
        for (int i = 0; i < 100; i++) {
    
            System.out.println(i);
        }

    }
}

Although all circular bodies can be used while perhaps do…while Realization , however java Provides another efficient statement .

for The nature of the cycle

• for A generic structure that supports iteration in a circular fashion , Is the most effective , The most flexible structure

• for The number of times the loop is executed is determined before execution

for Circulation and while Difference between cycles

1. for The number of times the loop is executed is determined before execution ,while Is to judge while executing .

for Attention to circulation

expression ：for（ Initial value ; conditional ; to update ）{ Output }

1. Initial value （ Optional ） The default is 0

2. conditional （ Optional ） The default is true

3. Update the iteration （ Optional ） Default continuous update

   for(;{} // Dead cycle

If 3 All conditions are empty , Will fall into the trap of while（true） The same loop

practice ：

need 1-1000 Between magic and even sum

package com.ckw.blog.select;

public class demo_for02 {
    
    // need 1-1000 Between magic and even sum 
    public static void main(String[] args) {
    
        int oddsum = 0;// Define an even number and a variable 
        int evensum = 0;// Define an odd number and a variable 
        for (int i = 0; i <=100; i++) {
    
            if (i%2!=0){
    
                oddsum+=i;
            }else {
    evensum+=i;};
        }
        System.out.println(" Even sum is "+oddsum);
        System.out.println(" Odd sum is "+evensum);
    }
}

To calculate the 1-1000 Can be 3 Divisible number , And change one line for every three numbers

package com.ckw.blog.select;

public class demo_for03 {
    
    // To calculate the 1-1000 Can be 3 Divisible number , And change one line for every three numbers 
    public static void main(String[] args) {
    
        for (int i = 0; i < 1000; i++) {
    
            if (i%3==0){
    
                System.out.print(i+"\t");
            if(i%9 == 0){
    
                System.out.println();
            }
            }
        }
    }
}

99 Multiplication table

Programming thinking

package com.ckw.blog.select;

public class demo_for {
    
    public static void main(String[] args) {
    

        //99 Multiplication table 
        /*  Print the first column first , Consider the second column after the first column is normal   And then put the fixed 1, Then wrap it in a circular package   Remove duplicates   Adjust the style again  */
        for (int j = 1; j <=9; j++) {
    
            for (int i = 1; i <= j; i++) {
    
                System.out.print(j+"*"+i+"="+j*j+"\t");
        }System.out.println();
        }

    }
}

Output triangle

package com.ckw.blog.select;

public class demo_3jiaoxing {
    
    public static void main(String[] args) {
    
        for (int j = 0; j <=5; j++) {
    
            for (int i = 5; i >=j; i--) {
    
                System.out.print(" ");
            }
            for (int i = 0; i <=j; i++) {
    
                System.out.print("*");
            }
            for (int i = j; i >0; i--) {
    
                System.out.print("*");
            }

            System.out.println("");

        }

    }
}

for Enhanced

Traversal array .

for（ Declare variables : Array ）{ Output }

package com.ckw.blog.select;

public class demo_for_04 {
    
    public static void main(String[] args) {
    
        // enhance for loop , Traversal array 
        int[] numbers ={
    10,20,30,40};
        for(int x:numbers){
    
            System.out.println(x);
        }
        // The original way of writing 
        for(int j=0;j<4;j++){
    
            System.out.println(numbers[j]);
        }
    }
}

Out of the loop

break Forcibly exit the loop , Do not execute the remaining statements in the loop .

continue Terminate a cycle , The rest are the same .

difference

break It's resignation ,continue It's asking for leave .

break

package com.ckw.blog.select;

public class demo_break_continue {
    
    public static void main(String[] args) {
    
        for (int i = 0; i < 100; i++) {
    
            System.out.println(i);
            if(i>50){
    break;}
        }
    }
}

continue

package com.ckw.blog.select;

public class demo_break_continue {
    
    public static void main(String[] args) {
    
        for (int i = 0; i < 100; i++) {
    
            if (i == 40){
    continue;}// If it is equal to 40, Just skip this loop 
            System.out.println(i);
        }
    }
}