A brief introduction to process control statements in PHP (with examples)

This article brings you a brief introduction to the process control statements in PHP (with examples). It has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.

1. Conditional judgment statement

if statement
1. Single-branch if statement
2. Double-branch if-else statement
3. Multi-branch if-elseif-else statement

$bool1 = true;
//if语句
if ($bool1) {
    echo '为真';
} 
//结果输出了 为真
//if-else语句
if ($bool1) {
    echo '为真';
}else {
    echo '为假';
}
//结果输出了 为真
//if-elseif-else多分支语句
$var1 = 86;
if ($var1<100) {
    echo &#39;小于100&#39;;
}elseif($var1>0){
    echo &#39;大于0&#39;;
}else{
    echo &#39;不在0-100的范围内&#39;;
}
//结果输出了 小于100

switch statement

• The parameter type in switch can only be an integer or a string

• No need to add {} to each case code block of switch

• There should be a break after each case, otherwise the execution of the next branch statement will continue

• The default clause is not necessary and can be omitted

$grade = mt_rand(0,100);
switch($grade){
    case $grade>90:        
    echo "$grade is A";        
    break;    
    case $grade>80:        
    echo "$grade is B";        
    break;    
    case $grade>70:        
    echo "$grade is C";        
    break;    
    case $grade>60:        
    echo "$grade is D";        
    break;    
    default:        
    echo "$grade is E";        
    break;
}

2. Loop control statement

1.while loop
2. do-while loop
3. for loop
4. foreach loop

//while循环
$a=1;
while ( $a<= 10) {
    echo $a++;
}
//结果为 12345678910
//do-while循环，会执行一次循环体，在判断条件
$b=10;
do{
    echo $b--;
}while($b>5);
//结果为 109876
//for循环
for ($i=0; $i <=10 ; $i++) { 
    echo $i;
}
//结果为 12345678910
//foreach循环
$array = array(1,3,5,7,9);
foreach($array as $key=>$value){
    echo $key.&#39;=>&#39;.$value.&#39; &#39;;
}
//结果为 0=>1 1=>3 2=>5 3=>7 4=>9

3. Jump control statement

1. break
　 statement is used for interruption Loop execution
    In multi-level loops, you can add a number after break to terminate the multi-level loop

2.continue
    Just jump out of this loop and continue the following loop

3. exit
ˆ ˆ Exit the current script, and subsequent statements will no longer be executed

//break
for ($i=0; $i <=10 ; $i++) { 
    if($i==5) break;//$i等于5时，跳出整个循环
    echo $i;
}
//结果为 01234
//continue
for ($i=0; $i <=10 ; $i++) { 
    if($i==5) continue;//$i等于5时，跳出本次循环
    echo $i;
}
//结果为 01234678910 没有5
//continue
for ($i=0; $i <=10 ; $i++) { 
    if($i==5) exit; //$i等于5时，跳出本次循环
    echo $i;
}
//结果为 01234
echo &#39;这里的输出也不会执行,脚本被停止&#39;;

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