Problem making previous next posts with php

user_16437084 0
Viewed 47

I searched everywhere and found out you can use "--" before and "++" after a variable to substract or increase it by 1, but it just wont work properly, here's my code

$sql=mysqli_fetch_array(mysqli_query($link ,'SELECT max(id) as cnt FROM products'));

$maxid = $sql['cnt'];
$minus = --$_GET['id'];
$plus  = $_GET['id']++;
    
if ($minus == '0')
{}
else 
{echo '<a style="float:left" href="/product/'.$minus.'">Previous offer</a>';}

if ($plus <= $maxid)
{echo '<a style="float:right" href="/product/'.$plus.'">Next offer</a>';}
else 
{}
php
3 Answers

i think u need use ++$_GET['id'] to get increased value.

user_66896220

You can read more on increment and decrement operators. It basically does not applies to what you want to achieve here using increment and decrement operators. You are using this operators which applies to your $_GET['id'] resulting in change in your $_GET['id'] itself.

Simply use $minus = $_GET['id']-1; $plus = $_GET['id']+1;

user_164781610

$_GET values are by default strings when you receive them from frontend. To make it work for your case, you need to convert that to integer first. You can of course make the code more shorter, but since you want to use increment or decrement operators, here is one way:

$minus = intval($_GET['id']);
$plus  = intval($_GET['id']);

--$minus;
$plus++;

You seem to be tempted to do,

$plus  = $_GET['id']++;

Post increment during an assignment is a bad practice, even if you know what you are doing. This can lead to long debugging hours if something goes wrong. You could rather assign the value to a variable and then do the increment or decrement operations as needed.

On further observation, primary key IDs need not be sequential. So, the approach of +1 or -1 won't work. I am keeping my above explanation as is to make you realize those few things.

user_49648220
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