What are the PHP control flow statements?

php control flow statements include: 1. If statement, if the condition is true, the code block here is executed; 2. Switch statement, if the value of the expression is equal to value1, then the code block here is executed; 3 , For loop, controls the number of loop executions according to a specific number of times; 4. While loop, used to repeatedly execute a certain piece of code when a certain condition is met, until the condition is no longer met.

The operating environment of this tutorial: The operating environment of this tutorial: windows10 system, php8.1.3 version, DELL G3 computer.

PHP is a commonly used server-side programming language with powerful control flow statements that can be used to control the execution sequence and conditions of the program.

1. If statement:

The If statement is used to determine whether to execute a certain code based on conditions. The syntax is as follows:

if(condition){
//如果条件为真，则执行这里的代码块
}

Among them, condition is a Boolean expression. If the value of the expression is true, the content in the if code block will be executed.

You can also use if-else statements to execute different blocks of code when the condition is true or false:

if(condition){
//如果条件为真，则执行这里的代码块
}else{
//如果条件为假，则执行这里的代码块
}

2. Switch statement:

## The #Switch statement is used to select and execute different blocks of code from a series of options based on the value of an expression. The syntax is as follows:

switch(expression){
casevalue1:
//如果表达式的值等于value1，则执行这里的代码块
break;
casevalue2:
//如果表达式的值等于value2，则执行这里的代码块
break;
default:
//如果表达式的值不等于任何一个case的值，则执行这里的代码块
break;
}

Among them, expression is an expression, and its value will be compared with the value of each case. If a certain case value is matched, the corresponding code block will be executed. If no case value is matched, the default code block will be executed.

3. For loop:

The For loop statement is used to repeatedly execute a certain piece of code, and can control the number of loop executions according to a specific number of times. The syntax is as follows:

for(initialization;condition;increment){
//每次循环都会执行这里的代码块
}
其中，initialization用于初始化循环控制变量;condition是循环继续执行的条件;increment用于更新循环控制变量的值。
也可以使用foreach循环来遍历数组或对象的每个元素：
foreach($arrayas$value){
//遍历数组的每个元素并执行这里的代码块
}

4. While loop:

While loop statement is used to repeatedly execute a certain code when a certain condition is met until the condition is no longer Until you are satisfied. The syntax is as follows:

while(condition){
//只要条件满足，就会重复执行这里的代码块
}
其中，condition是一个布尔表达式，只要表达式的值为真，就会循环执行代码块。
还有do-while循环语句，它与while循环的区别在于它是先执行代码块，再判断条件是否满足：
do{
//先执行这里的代码块
}while(condition);

To sum up, PHP's control flow statements include if statements, switch statements, for loops, foreach loops, while loops and do-while loops. By using these statements appropriately, we can control the execution sequence and conditions of the program and achieve more precise program logic control. .

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