I. JavaScript Programming Problem
Enter a year (to be verified) on the page to determine whether it is a leap year (year divisible by 4, but not by 100; leap year divisible by 400), and display the corresponding prompt information on the page.
(1) Code
<!doctype html>
<html>
<head>
<title>Leap year</title>
<meta charset="utf-8">
</head>
<body>
<form>
//Please enter the year: <input id="year" type="text"/>
<text id="check"></text>
</form>
<script>
var input = document.getElementById("year");
var tip = document.getElementById("check");
//Input Box Loss Focus Trigger Event
input.onblur = function() {
var year = input.value.trim();
//Year consists of four digits
if(/^\d{4}$/.test(year)) {
//A year divisible by four but not by 100; a leap year divisible by 400
if((year % 4 == 0 && year % 100 != 0) || (year % 400 == 0)) {
tip.innerHTML = "Leap year";
} else {
tip.innerHTML = "Non leap year";
}
} else {
tip.innerHTML = "The format of the year is incorrect. Please re-enter it.";
}
}
</script>
</body>
</html>
(2) Operational screenshots
MySQL Questions and Answers
How do I log in to MySQL through a command prompt? How to list all databases? How to switch to a database and work on it? How to list all tables in a database? How do I get the names and types of all Field objects in the table?
Answer:
- mysql -u -p
- show databases;
- use dbname;
- show tables;
- describe table_name ;
3. Java programming problems
If a number is exactly equal to the sum of its factors, it is called a "perfect number". For example, 6 = 1 + 2 + 3. Programming finds all completions within 1000.
(1) Code
package com;
public class daily0801 {
/**
* Judging whether it is a perfect number
*
* @param a
* Numbers to be judged
* @return boolean
*/
public static boolean test(int a) {
int sum = 0;
// Cyclic traversal, find all the factors, and calculate the sum of the factors
for (int i = 1; i < a; i++) {
if (a % i == 0)
sum = sum + i;
}
return (sum == a);
}
public static void main(String[] args) {
for (int i = 1; i < 1000; i++) {
if (test(i)) {
System.out.println(i);
}
}
}
}
(2) Operational screenshots