Use php+mysql to make a powerful online calculator_PHP tutorial

After searching for a long time, I found that there was very little information on the Internet, so I wanted to write it myself. Gradually, I found that there were many problems. I was not very good at algorithms. It was okay to write a short calculation formula, but it would fail if it was too long. If it was longer, I would be afraid. It's about to crash.

One day while doing mysql, I suddenly discovered that mysql is so powerful that it can directly calculate strings. . . Haha, I’m so happy now.

The code is super simple and I made an ajax calculator

There are formula error prompts and the entered formula can be displayed at all times

Interested friends can take a look You can develop more functions by yourself

Demo address: http://www.jianlila.com/jsq.php

Download jquer.js yourself

jsq1. php

Copy code The code is as follows:

//
$db that links the database =mysql_connect("localhost","root","123");
header("Content-Type:text/html;charset=GB2312");
$str=iconv('utf-8', 'gbk',trim($_POST['t_ask']));
$str=str_replace(" ","",str_replace("rn","",$str));
$str= str_replace("（","(",$str);
$str=str_replace(")",")",$str);
/*Trigonometric function replacement*/
$str= preg_replace("/sin((.*))/is","sin(${1}*pi()/180)",$str);//Replace sin
$str=preg_replace("/cos ((.*))/is","cos(${1}*pi()/180)",$str);//Replace cos
$str=preg_replace("/tan((.*) )/is","tan(${1}*pi()/180)",$str);//Replace tan
$str=preg_replace("/cot((.*))/is", "1/tan(${1}*pi()/180)",$str);//Replace cotangent
$str=preg_replace("/asin((.*))/is","asin (${1}/pi()*180)*180/pi()",$str);//arcsine
$str=preg_replace("/acos((.*))/is"," acos(${1}/pi()*180)*180/pi()",$str);//Inverse cosine
$str=preg_replace("/atan((.*))/is", "atan(${1}/pi()*180)*180/pi()",$str);//Replace arctangent
$sql="select ".$str;
$res= mysql_query($sql,$db) or die('The formula you entered is wrong');
$rs=mysql_fetch_array($res);
echo $rs[0];
?>

jsq.php

Copy code The code is as follows:

< ;script src="jquery.js" language="javascript">

Handwriting input calculator

< ;tr>

Here you can calculate by handwriting, why not give it a try! Return to homepage

> ;

Calculation formula:
=

Instructions:

Trigonometric functions:

sin(60) sine cos(60) cosine tan (60) Tangent cot(60) Cotangent

asin(0.5) Arcsine acos(0.5)
Arccosine atan(0.5) Arctangent

abs(-1) =1 absolute value ceil(0.1)=1 into one

Exponential logarithm

exp(float arg)// Calculatee(natural logarithm The exponent of the base)

log(10,100)=2//natural logarithm pow(2,4)=16 exponent sqrt(4)=2 square root

http://www.bkjia.com/PHPjc/322555.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/322555.htmlTechArticleAfter searching for a long time, I found that there was very little information online, so I wanted to write it myself, but slowly I found that there were more questions. I’m not very good at algorithms. It’s better to write a short calculation formula, but it will fail if it’s too long. Then...