Share interests, spread happiness, increase experiences, and leave beauty!
Dear, this is LearningYard New School.
Today, the editor will bring you a 29-JavaScript loop to you, welcome to visit.
Share interests, spread happiness, increase knowledge, and leave a good legacy!
Dear you, this is The LearningYard Academy.
Today Xiaobian brings you Knowledge set| Flexsim modeling and simulation of warehouse systems, welcome to your visit.
Why do we use loops:
When writing code, we often want to execute the same piece of code repeatedly. At this time, we can use loops to complete this function, so that we need to write several lines of the same code without repeated repetition.
Example: I want to output 100 lines I love you. (This is the repeated output I love you, but it will be too troublesome if we copy and paste)
At this time, we can use loops to help us do this repetitive thing.
Why do we use loops:
When writing code, we often want to execute the same code repeatedly. At this time, we can use the loop to complete this function, so that we don't have to write several lines of the same code repeatedly.
For example: I want to output 100 lines. I love you. (Here, I just keep repeating that I love you, but it's too much trouble if we copy and paste it.)
At this time, we can make use of the cycle to help us do this repetitive thing.
js loops are divided into three types: while loop, do-while loop, for loop
loop elements: initialization variables, conditional expressions, executing code, and changing itself.
while loops are often used in situations where you don't know the number of loops. For example, let the user loop enter an integer until a special character is entered, and you can't even finish the number of times the loop will go.
syntax:
while (conditional expression){
State block to be executed when the conditional expression is boolean true
There are three kinds of loops of s: while loop, do-while loop and for loop.
Loop elements: initialization variables, conditional expressions, execution codes, and self-changes.
While loop is often used in situations where you don't know the number of loops. For example, you can't know the number of times this loop will be performed until a special character is entered.
Grammar:
While (conditional expression) {
A statement block to be executed when the conditional expression is boolean true.
}
do-while and while loops are different in that it first executes the statement in the loop, and then judges whether the expression is true. If it is true, continue the loop; if it is false, terminates the loop. Therefore, the do-while loop must execute the loop statement at least once.
Syntax:
do{
Statement block executed when the conditional expression is true
}while (conditional expression)
Do-while loop differences from while loop in that it first executes the statements in the loop, then determines whether the expression is true, and if it is true, it continues the loop; If false, the loop is terminated. Therefore, the do-while loop must execute the loop statement at least once.
Grammar:
do{
Statement block executed when the expression is true
}while (conditional expression)
for loop is mostly used in situations where the number of loops is clear, which is the kind of situation where you can see how many times you need to loop at a glance. It is more intuitive. The first sentence of the for loop contains the initialization of the variable. The conditions for ending the loop and the value updated each time, and the real thing to do is executed inside the loop body. For example, for(n=1;n10;n++), is generally used for traversal and is a relatively used loop method.
Syntax:
for(variable initialization; conditional expression; variable update){
State block
}
For loop is mostly used when the number of loops is clear, that is, it can be seen at a glance how many times to loop, which is more independent. The first sentence of the for loop contains the conditions for the initialization of variables to end the loop and the value updated each time, so that what really needs to be done is executed inside the loop body. For example, for(n=1; n10; ++), which is generally used for traversal, is a circular way of comparative use.
Grammar:
For (variable initialization; Conditional expression; Update) {
Execute the statement block when the expression is true.
}
loop nesting refers to the syntax structure of defining a loop statement in a loop statement. For example, in a for loop statement, a for loop can be nested. We call such a for loop statement double for loop.
outer layer loops once, and the inner for loop is all executed and then the outer layer loop is performed;
Note: Double for loop is to nest another for loop in one for loop, that is, two loops are nested, and multiple loops are nested, but it is used relatively less. Generally, two loops are nested, and multiple loops are rarely used, because too many for loops will lead to low code execution efficiency and are prone to crash. The total number of loops in multiple loops is multiplied, and the geometric series grows after several nesting times. Therefore, we usually do not recommend using it when loops are nested multiple times.
Loop nesting referers to defining the syntax structure of another loop statement in a loop statement. for example, in a for loop statement, another for loop can be nested. Such a for loop statement is called double for loop.
The outer layer is circular once, and the inner layer for circuit is completely executed, and then the outer layer is circular once;
Note: Double for loop is to nest another for loop in one for loop, that is, two loops are nested, and multiple loop is nested. However, it is seldom used. Generally, two loops are nested, and multiple loop is seldom used, because too many for loops will lead to low efficiency of code execution, and it is easy to crash. The total number of loops in multiple loops is multiplied, and geometric progression increases after nesting several times. Therefore, we usually do not recommend using it when loops are nested many times.
That's all for today's sharing.If you have any unique ideas about today's article, please leave a comment and leave a message. Let's make an appointment tomorrow. I wish you a happy and happy day!
That's it for today's sharing. If you have any unique ideas for today's article, please leave a comment, let us meet tomorrow, I wish you a happy day!
Translation: Google Translation
This article is original by LearningYard New Academy, and some pictures and texts are from the Internet. If there is any infringement, please contact us.
Text & Typesetting | Li Shiyang
Review | Li Huan
