Student Wang traveled back and forth between Beijing and Dalian repeatedly, and recorded the number of round trips in his notebook. There is another implementation in PHP that can achieve the same counting.

The for loop is a counting loop in PHP, and its syntax is quite variable. This is a knowledge point that must be mastered.

for (表達(dá)示1; 表達(dá)示2; 表達(dá)示3){
        需要執(zhí)行的代碼段
}

• Expression 1 is an initialization assignment, and multiple codes can be assigned at the same time.
• Expression 2 is evaluated before each loop starts. If the value is TRUE, the loop continues and the nested loop statement is executed. If the value is FALSE, the loop is terminated.
• Expression 3 is evaluated after each loop.

Let’s write a simple example and see:

<?php
for ($i = 1; $i <= 10; $i++) {
    echo '分手后第'.$i.'年，我全都忘了你的樣子<br />';
}
?>

In other words, let’s try to judge multiple conditions:

<?php
    for($i=0,$j=10;$i<$j;$i++,$j--){    
    echo $i.'---------'.$j.'<br />';
    }
?>

We use for Let’s type the 9*9 multiplication table in a loop. The demonstration effect is as follows:

Remember during the analysis and thinking process: the code is output horizontally

<?php

//99乘法口訣表從1開始，所以聲明一個(gè)變量$i = 1,讓$i小于10，也就是最大值為9
for($i = 1 ; $i < 10 ; $i++ ){
        //1x1=1，2x2等于4，所以第二次循環(huán)的最大值為$i的值，因此$j＝1, $j在循環(huán)自加的過程當(dāng)中，只能夠小于等于$i

    for($j=1;$j<=$i;$j++){
                //  1 x 2 = 2   2 x 2 = 4啦
        echo $j . 'x' . $i . '=' .($i*$j) . '&nbsp;&nbsp;&nbsp;';
    }
    echo '<br />';

}

Let's try break, exit and continue to control the 9*9 multiplication table.

##exitBefore exit We have talked about stopping subsequent execution from the current locationbreakI have encountered it before, jumping out of the loop or structure to execute subsequent codecontinueJump out of this loop and continue the next loop

Statement	Function

Let’s demonstrate break and continue:

<?php
for ($i = 1; $i <= 10; $i++) {

    if($i == 4){
            //待會(huì)兒換成continue試試
            
            break;
    }

    echo '分手后第'.$i.'年，我全都忘了你的樣子<br />';
}
?>

$i is equal to 4, the effect of break is as follows:

Note: No longer executed after the 4th point in the above figure

$i is equal to 4, the effect of continue is as follows:

Note : The 4th one in the picture above is lost, and then the

---

job is continued from the 5th year:

Use a single-layer for loop to control the table that changes color on alternate rows

Use the double-layer loop of for to control the color-changing table of alternate rows
Write 99 multiplication tables silently, and experiment with continue and break at the positions of $i and $j in the middle;