Warning: Invalid argument supplied for foreach() in Php: This warning comes when you are not passing array to foreach. To fix this warning you can use is_array to check the argument type supplied to foreach. Here is an example – How to fix Warning: Invalid argument supplied for foreach().

Warning: Invalid argument supplied for foreach() in Php

Add the is_array() method to fix the warning –

$array = array("John", "Rimmy", "Kelly");
//now add the following check 
if(is_array($array)){
foreach($array as $data){
echo $data;
}

}

The above check will fix your problem.

PHP Check that variable is an array : PHP function is_array is used to check a variable whether it is array or not. it accepts one parameter as variable and finds it is array or not. Returns true if the variable is array else it returns false. Here we are going to explain this function with example –

PHP Check that variable is an array

Here is an example of how to check a variable is array or not –

$array = array('a', 'b', 'c');

if(is_array($array)){
echo "This is array.";
}else{
echo "This is not array.";
}
//will print - This is array

The above example will print – This is array because we passed array variable to check.

Now lets go with another example which is not array

$str = "abcd";

if(is_array($str)){
echo "This is array.";
}else{
echo "This is not array.";
}
//will print - This is not array

The above example will print – This is not array because we passed string variable to check and this function will refurn false so it will go in else condition.

PHP Implode function – It converts array into string. This function accepts array elements and returns the string of elements separated by delimiter. The function explode is reverse of the implode function. Both implode and explode functions are frequently used functions in php. We are going to describe the implode function with example and demo.

PHP Implode function Syntax

implode(separator, array);

Input Parameters

• separator : Is used to put separator between array element you can pass null as “” if do not want to put anything between elements.
• array : Array you want to convert to string.

Return value

It returns string.

Technical Requirement-

PHP Version : 4+

Let us understand implode function with examples.

PHP Implode function Example

Here is very basic example –

$array = array('a','b','c','d');
$string = implode(" ", $array);
echo $string;

In the above example array elements converted into string by separator space. The above example will produce the following outut-

PHP implode array comma separated Example

Here is another example with separator comma “,” –

$array = array('a','b','c','d');
$string = implode(",", $array);
echo $string;

The above example will produce following output-

PHP implode array pipe separated Example

Here is another example with separator pipepline “|” –

$array = array('a','b','c','d');
$string = implode("|", $array);
echo $string;

The example will convert the array elements to string by pipeline separator. Here is the output of the above example –

If you want to perform reverse of this function use the function explode.

PHP htmlspecialchars Function : It converts Special Characters to HTML entities. This function returns the converted result as string. This function has its own significance and used frequently. The opposite of this functions is htmlspecialchars_decode(). We are going to explain this example with example and demo.

Let us understand the htmlspecialchars with very basic example – We have some raw data like this – <b>Hi it’s me John</b> now what would happen when user see form data on browser it will show something bold string like this – Hi it’s me John which is wrong because it should show output like this – <b>Hi it’s me John</b> . Now to fix this problem convert HTML tags to its equivalent entities. This is done by using the function htmlspecialchars().

PHP htmlspecialchars Function Syntax

It Converts the following HTML Characters only –

• &(ampersand) = &
• ” (double quote) = "
• ‘ (single quote) = '
• < (less than) = <
• > (greater than) = >

Here is syntax for the function htmlspecialchars –

htmlspecialchars(string,flags,char-set,double_encode)

Input Parameters

• string: String to be converted.
• flag:flag is optional . This is basically used to specify how to handle the quotes and which document type use.

Here are following flags available-

• ENT_COMPAT : This is default. Encodes only Double Quotes
• ENT_QUOTES : This Encodes Both Single and Double Quotes.
• ENT_NOQUOTES : Encodes neither Single nor Double Quotes.
• ENT_IGNORE : Ignore invalid code unit sequences instead of returning empty string.
• ENT_SUBSTITUTE : Replace invalid code unit sequence with a unicode replacement
  charecter U+FFFD (UTF-8) or &#FFFD; (otherwise) instead of returning an empty string
• ENT_DISALLOWED : Replace invalid code points in the given document type with a Unicode Replacement Character U+FFFD (UTF-8) or &#FFFD;.
• ENT_HTML401 : Handle code as HTML 4.01.
• ENT_XML1 : Handle code as XML 1.
• ENT_XHTML : Handle code as XHTML.
• ENT_HTML5 : Handle code as HTML 5.
• char-set: This is optional parameter. This is basically used to decide which character set to use.
  • UTF-8 : This is Default ASCII Compatible Multi byte 8-bit Unicode.
  • ISO-8859-1 : Western European, Latin-1.
  • ISO-8859-15 : Western European, Latin-9
  • cp866: DOS-specific Cyrillic charset
  • cp1251 : Windows-specific Cyrillic charset.
  • cp1252 : Windows specific charset for Western European
  • KOI8-R : Russian.
  • BIG5 : Traditional Chinese, Specially used in Taiwan.
  • GB2312 : National standard character set.
  • BIG5-HKSCS : Traditional Chinese.
  • Shift_JIS SJIS, SJIS-win, cp932, 932 Japanese
  • EUC-JP :Japanese
  • MacRoman : Charset that was used by Mac OS.
• double_encode: This is optional parameter which decides whether to encode existing htmlentitis or not. It accepts TRUE and FALSE as parameter.
  • TRUE: Encode Everything.
  • FALSE: Do not encode existing htmlentities.

Return Values

This function returns the encodeed string.

Php Version

Supports in php 4+

PHP htmlspecialchars function example

$string = "Hi it's me John";
echo htmlspecialchars($string);

Above Example will produce following output-

HTML Output

Browser Output

PHP htmlspecialchars function example

$string = '"Hello World"';
echo htmlspecialchars($string);

HTML Output

Browser Output

PHP htmlspecialchars vs htmlentities

The difference between htmlspecialchars and entities is given below-

• htmlentities — Converts/Encodes all applicable characters to HTML entities.
• htmlspecialchars — Converts/Encodes only special characters to HTML entities.
• htmlspecialchars does not converts all characters having their html equivalent.
• If output is XML you can’t use HTML entities in a XML file.
• htmlentities converts more characters than htmlspecialshars so htmlspecialchars is more efficient.
• If your page have encoding ASCII or LATIN-1 use htmlentities else use htmlspecialchars.

Read full documentations about htmlentities with example and demo – htmlentities

PHP htmlspecialchars reverse

If want to perform reverse operation of htmlspecialchars use – htmlspecialchars_decode.

Try Video Demo – All In One Video for this method –