Converting strings and quoted-printable characters in PHP

In the previous article, we learned about the method of removing the characters on the right side. If necessary, please read "php String Challenge: Removing the Characters on the Right Side". This time we will introduce to you the method of converting strings and quoted-printable characters to and from each other. You can refer to it if you need it.

Before starting to study this article, let’s first take a look at what is quoted-printable.

Quoted-printable can be translated as "printable character reference encoding" and "encoding using printable characters". When we receive emails and check the original information of the letter, we often see this type of encoding!

It is an implementation of Multipurpose Internet Mail Extensions (Mime). Mime is an Internet standard that extends email standards and strives to support various formats of email, such as non-ASCII characters, binary format attachments, etc. Currently, many HTTP protocols use mime frames! Quoted printable refers to using some common printable characters to represent all non-printable characters in one byte (8 bits)!

After having an understanding of Quoted-printable, let’s start our topic.

First we need to convert the string into Quoted-printable, so that the Quoted-printable string can be converted into ordinary characters.

Let’s look at a small example.

<?php 
$str = quoted_printable_encode("Hello
Aworld.");
echo($str); 
?>

The result of this is

Let’s see if this result is a bit strange. This “=0A” is How it came out? Let's look at the code. We used the line break key on the keyboard after the word hello. Although this is no problem in ordinary HTML or PHP, no line break occurs. But in this function, no, it will parse out the Enter key.

After understanding this, let’s introduce this function in detail.

quoted_printable_encode() The function converts a 8 digit string into a quoted-printable string.

In fact, its syntax is very simple, just

quoted_printable_encode(string)

But we need to pay attention when using this function:

After Quoted-printable encoded data is not the same as modified data transmitted via mail. A fully US-ASCII text can be quoted-printable encoded to ensure data integrity when messaging via text translation or wirepack gateways.

Next, let’s restore the quoted-printable encoded data.

Let’s restore the data in the above example.

<?php 
$str = quoted_printable_decode("Hello=0AAworld.");
echo($str); 
?>

When this example is output in the browser

When this example is output in html

With this comparison, you can see the difference. The code decoded by this function will not display the decoding result of "=0A" on the browser, but there will be specific results in the html Effective.

That’s all. If you want to know anything else, you can click here. → →php video tutorial

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