PHP using explode to split the string novice easy to ignore problems

1.explode Method Description

The Explode method allows a string to be split into groups by one string as a boundary point.

Array explode (string $delimiter, string $string [, int $limit]) 1

Returns an array of strings, each of which is a substring of string, separated by the delimiter as the boundary point.

parameter Description:
Delimiter
The delimited character on the boundary.

String
The input string

Limit
If the limit parameter is set and is a positive number, the returned array contains a maximum of limit elements, and the last element will contain the remainder of the string.
If the limit parameter is a negative number, all elements except the last-limit element are returned.
If limit is 0, it will be treated as 1.

2. Example

Use, split string

 
  ';p rint_r ($arr); Echo '

';? >1234567

Output:

Array (    [0] = 1    [1] = 2    [2] = 3    [3] = 4    [4] = 5    [5] = 6    [6] = = 7
  
   [7] = 8    [8] = 9) 123456789101112
  

Use, split string, limit is positive

 
  ';p rint_r ($arr); Echo '

';? >1234567

Output:

Array (    [0] = 1    [1] = 2    [2] = 3    [3] = 4    [4] = 5,6,7,8,9) 12345678

Use, split string, negative limit

 
  ';p rint_r ($arr); Echo '

';? >1234567

Output:

Array (    [0] = 1    [1] = 2    [2] = 3    [3] = 4    [4] = 5    [5] = 6) 123456789

Use, split string, limit is 0

 
  ';p rint_r ($arr); Echo '

';? >1234567

Output:

Array (    [0] = 1,2,3,4,5,6,7,8,9) 1234

3. Easy to ignore problems

In general, we use explode to split data such as ID strings.

 
  $v) {        //do sth    }}?>123456789

Under normal circumstances, IDS is not empty, look at the code will not find any problem, because there is a judgment if (data), it is generally considered to have done an empty processing.
But the reality is ids=null, but data is not empty, causing problems with the code executing in foreach.

 
  123456789

Because Ids=null, the array ([0] = =) instead of array () is derived using explode.

So the judgment needs to be modified to avoid problems.

 
  $v) {        //do sth    }}?>

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