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Detailed introduction to PHP knowledge points

巴扎黑
Release: 2023-03-10 09:20:01
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Problem In javascript, both integers and floating-point numbers belong to the Number data type (one of the simple data types). We often find that when printing a floating-point number such as 1.0, the result is 1 instead of 1.0. This is due to saving the floating-point number. Points take up twice as much memory as storing integer values, so ECMAScript wastes no time converting floating point numbers to integers. Although the above situation makes patients with obsessive-compulsive disorder a little uncomfortable, it is not a big mistake anyway. The next situation will be very scary. For example, when we calculate 0.1 plus 0.2, the output result is not 0.3, but 0.3000000000000004. what the fuck? ! For children who encounter this situation for the first time, do you feel that your world view has been challenged? The reason was so I quickly opened the book to save my soul and body, and found that it was clearly written in the book: ECMAScrip is based on IEEE754 numerical floating point calculation. If you don’t know what IEEE754 is, click here. This numerical calculation method will save the value as Binary is then calculated. Since floating point numbers are infinite when expressed in binary, there will be

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Detailed introduction to PHP knowledge points

##Introduction: In javascript, both integers and floating point numbers belong to the Number data type (one of the simple data types). We often It is found that the result of printing a floating point number such as 1.0 is 1 instead of 1.0. This is because the memory space for storing floating point numbers is twice that of storing integer values, so ECMAScript will lose no time in converting floating point numbers into integers. Although the above situation makes patients with obsessive-compulsive disorder a little uncomfortable, it is not a big mistake anyway. The next situation will be very scary. For example, when we calculate 0.1 plus 0.2, the output result is not 0.3, but 0.3000000000000004. what the fuck? ! The children's shoes who encountered this situation for the first time are

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##10. Ask for {dede:sql} How to write PHP native code in tag script! Solution

## Introduction: How to write PHP native code in {dede:sql} tag script! ='...' runphp='yes'} echo 'fuck'; {/dede:sql} It's useless for me to write like this. How can I write php native code in the {dede:sql} tag script??------Solution-----------

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