Solving PHP Error: Things to Consider When Converting an Array to a String

Question

I have a PHP file and I'm trying to output a $_POST, but I get an error, and here's the code: echo"&lt;html&gt;";echo"&lt;body&gt;";for($i=0;$i&lt;5 ;$i++){echo"&lt;inputname='C[]'value='$Texting[$i]'"

P粉986860950 · Answer

The meaning of PHP Notice and how to reproduce it:

If you pass a PHP array to a function that expects a string, such as echo or print, then the PHP interpreter will convert your array to a literal stringArray, throw this Notice and continue execution. For example:

php> print(array(1,2,3))

PHP Notice:  Array to string conversion in 
/usr/local/lib/python2.7/dist-packages/phpsh/phpsh.php(591) :
eval()'d code on line 1
Array

In this case, the function print outputs the literal string Array to stdout, then logs the Notice to stderr and continues execution.

Another PHP script example:

Correction method 1: Use foreach loop to access array elements

http://php.net/foreach

$stuff = array(1,2,3);
foreach ($stuff as $value) {
    echo $value, "
";
}

Output:

1
2
3

Or contain array key name:

$stuff = array('name' => 'Joe', 'email' => 'joe@example.com');
foreach ($stuff as $key => $value) {
    echo "$key: $value
";
}

Output:

name: Joe
email: joe@example.com

Note that array elements can also be arrays. In this case, you can use foreach again or use array syntax to access the inner array elements, like $row['name']

Correction method 2: Connect all cells in the array together:

If it is just an ordinary one-dimensional array, you can use the delimiter to concatenate all cells into a string:


Correction method 3: Convert array of complex structure to string:
If your array has a complex structure but still need to convert it to a string, you can use http://php.net/json_encode
$stuff = array('name' => 'Joe', 'email' => 'joe@example.com');
print json_encode($stuff);
Output: 
{"name":"Joe","email":"joe@example.com"}
Quickly view the array structure: use the built-in php function
 If you just want to inspect the array contents for debugging purposes, you can use one of the following functions. Keep in mind that var_dump is the most verbose of them all and is usually preferred for this purpose

http://php.net/print_r
http://php.net/var_dump
http://php.net/var_export

Example:
$stuff = array(1,2,3);
print_r($stuff);
$stuff = array(3,4,5);
var_dump($stuff);
Output: 
Array
(
    [0] => 1
    [1] => 2
    [2] => 3
)
array(3) {
  [0]=>
  int(3)
  [1]=>
  int(4)
  [2]=>
  int(5)
}

P粉739886290 · Answer

When you have a lot of HTML input named C[], what you get on the other end of the POST array is an array of those values $_POST['C'] . So when you echo it, you are trying to print an array, so it will just print Array and a hint.

To properly print an array, you can loop through it and echo each element, or you can use print_r.

Also, if you don't know if it's an array or a string or whatever, you can use var_dump($var) and it will tell you what type it is and what its contents are . For debugging purposes only.