Comparison of foreach () in PHP

PHP foreach () has two usage methods:

The first usage of PHP foreach:

 
 

  
  
foreach(array_nameas$value)  
  
  
{  
  
  
statement;  
  
  
}  
 
 

Here, array_name is the name of the array to be traversed. In each loop, the value of the current element of the array_name array is assigned to $ value, and the downloading inside the array is moved one step down, that is, the next element is returned in the next loop.

The second usage of PHP foreach:

 
 

  
  
foreach(array_nameas$key=>$value)  
  
  
{  
  
  
statement;  
  
  
}  
 
 

The difference between PHP foreach () and the first method is that there is an extra $ key, that is, in addition to assigning the value of the current element to $ value, the key value of the current element is also assigned to the variable $ key in each loop. The key value can be either a lower mark value or a string. For example, "0" in book [0] = 1 and "id" in book [id] = "001 ".