About the use of htmlentities, Htmlspecialchars, addslashes

1. Html_entity_decode (): Converts an HTML entity to a character.

Eg: $str = "Just atest & & #039; Learn to use & #039; ";

echo Html_entity_decode ($STR);

echo "<br/>";

Echo Html_entity_decode ($str, ent_quotes);

echo "<br/>";

Echo Html_entity_decode ($str, ent_noquotes);

The output is as follows:

Just a Test & ' learn to use '
Just a Test & ' learn to use '
Just a Test & ' learn to use '

2. Htmlentities (): Converts a character to an HTML entity.

Eg: $str = "Just a Test & ' learn to use '";

Echo htmlentities ($str, Ent_compat);

echo "<br/>";

Echo htmlentities ($str, ent_quotes);

echo "<br/>";

Echo htmlentities ($str, ent_noquotes);

The output is as follows:

Just a Test & ' learn to use '
Just a Test & ' learn to use '
Just a Test & ' learn to use '

View the source code as follows:

Just a test &amp; ' Learn to use ' <br/>

Just a test &amp; & #039; learn to use& #039; <br/>

Just a test &amp; ' Learn to use '

3. Addslashes (): Adds a backslash before the specified predefined character

Predefined characters include: Single quotation mark ('), double quotation mark ("), backslash (\), NULL

By default, PHP instruction MAGIC_QUOTES_GPC is on, and automatically runs Addslashes () for all get, POST, and cookie data. Do not use Addslashes () for strings that have been MAGIC_QUOTES_GPC escaped, because this results in double-layer escaping. You can use the function GET_MAGIC_QUOTES_GPC () to detect this situation.

Eg: $str 3= "\ just a" \ "test";

Echoaddslashes ($str 3);

Output:

\ \ just a \ ' \ "Test

4. Stripslashes (): Remove the backslash added by the addslashes function

Eg: $str 4= "\ \ Just a \ '" Test ";

Echo stripslashes ($str 4);

Output:

Just a ' "test

5, Htmlspecialchars (): Convert some of the predefined characters to HTML entities.

Predefined characters including:& (and) become &amp;
"(double quotes) become &quot;
' (single quotes) become & #039;
< (less than) becomes &lt;
> (greater than) becomes &gt;

Eg: $str 5 = "Just atest & ' Learn to use '";

Echo Htmlspecialchars ($str 5, Ent_compat);

echo "<br/>";

Echo Htmlspecialchars ($str 5, ent_quotes);

echo "<br/>";

Echo Htmlspecialchars ($str 5, ent_noquotes);

Output:

Just a Test & ' learn to use '
Just a Test & ' learn to use '
Just a Test & ' learn to use '

View Source code: Just a Test &amp; ' Learn to use ' <br/>
Just a test &amp; & #039; learn to use& #039; <br/>
Just a test &amp; ' Learn to use '
6, Htmlspecialchars_decode (): Convert some of the predefined HTML entities to characters.

HTML entities that will be decoded include:&amp; Become & (and No.)
&quot; Become "(double quotes)
& #039; Become ' (single quote)
&lt; Become < (less than)
&gt; Become > (greater than)

Eg: $str 6 = "Just atest &amp; & #039; learn to use& #039; ";

Echo Htmlspecialchars_decode ($str 6);

echo "<br/>";

Echo Htmlspecialchars_decode ($str 6, ent_quotes);

echo "<br/>";

Echo Htmlspecialchars_decode ($str 6, ent_noquotes);

Output:
Just a Test & ' learn to use '
Just a Test & ' learn to use '
Just a Test & ' learn to use '
View Source code:
Just a Test & & #039; Learn to use & #039; <br/>
Just a Test & ' learn to use ' <br/>
Just a Test & & #039; Learn to use & #039;

So far, I think we should understand the basic trial of several functions.

About the use of htmlentities, Htmlspecialchars, addslashes