PHP Tutorial foreach unset

First, we use an array to simulate a parameter pass. Received is a set of IDs, which I name here $nums:

$nums [] = 1;

$nums [] = 2;

$nums [] = 3;

$nums [] = 4;

We then use the $data array to touch the contents of a data table, with ID, username:

$data [0][' id '] = 1;

$data [0][' name '] = ' aaa ';

$data [1][' id '] = 2;

$data [1][' name '] = ' BBB ';

$data [2][' id '] = 3;

$data [2][' name '] = ' CCC ';

$data [3][' id '] = 4;

$data [3][' name '] = ' ddd ';

Next, we use the $rs array to touch the contents of another table, and correspondingly, with the same ID, and then the table contains the phone number:

$rs [0][' id '] = 1;

$rs [0][' mobile '] = ' 1111111 ';

$rs [1][' id '] = 2;

$rs [1][' mobile '] = ' 2222222 ';

$rs [2][' id '] = 10;

$rs [2][' mobile '] = ' 3333333 ';

$rs [3][' id '] = 4;

$rs [3][' mobile '] = ' 4444444 ';

Now all we have to do is to read out the username and phone number corresponding to the ID from the two arrays of $data and $rs, and display it in the list:

Echo ' <table width=400 align=center border=1> ';

foreach ($nums as $k => $v) {

Simulate reading data from $nums = = $data [' id '] in the database, get user name

foreach ($data as $KD => $vd) {

if ($v = = $VD [' id ']) {

$names = $vd [' name '];

}

}

Simulate reading data in the database $nums = = $rs [' id '], get the cell phone number

foreach ($rs as $kr => $vr) {

if ($v = = $VR [' id ']) {

$mobile = $VR [' Mobile '];

}

}

Echo ' <tr>

<td> '. $v. ' </td>

<td> '. $names. ' </td>

<td> '. $mobile. ' </td>

</tr> ';

}

Echo ' </table> ';

Then, after writing here, I ran this page, but when I ran out of the page, I found that something was wrong:

As shown in the figure, the number of the user ID = = 3 is changed to the number of id = 2.

Why is this? Let's take a look at our code:

First, the "id" in the $nums array is 1,2,3,4 Yes, $data the "id" in the array is also 1,2,3,4 Yes, but there is a problem with the "id" in the $rs array, which is 1,2,10,4. There's No 3 here.

So the phone number is not read. But why does the phone number show the phone number of id = 2 in the column ID = 3? We went on to look down:

Simulate reading data in the database $nums = = $rs [' id '], get the cell phone number

foreach ($rs as $kr => $vr) {

if ($v = = $VR [' id ']) {

$mobile = $VR [' Mobile '];

}

}

We are here to give $mobile the value of the assignment, when the "id" in the $nums equals the "id" in the $RS, it assigns the phone number in the $rs to the $mobile variable, and when the third loop is performed after ID = 2, we find that the condition does not match, so we jump directly It's over. However, the value of the $mobile is still the value of id = = 2! Right. That's the problem!

After I found the problem, I took a rest, drank a sip of cold water, and gave all the loop variables to unset () before the end of the foreach statement.