The difference between php reference and copy

Regarding value passing and reference passing, the explanations in books are relatively cumbersome, but they always appear in PHP interviews. Below, I will use a life example to help you understand the difference between them.

Step 1

Suppose we go to a hotel to book a room. We compare the hotel's house number to a variable name, and we use the number of people in the room as the variable name. The process of assignment

Characteristics of value transfer:

1. Value equality

That is, $k1 to $k2 The people in the room are equal.

2. Mutual independence and no influence on each other

That is to say, the number of guests in my $k1 room and the number of guests in my $k2 room do not affect each other. . This is called: "Different ways do not work together."

Second step

Take the above example and assume that our room $k1 is hung up by the maintenance worker with two house numbers $k1 and $k2 to understand

Characteristics of reference passing:

mutual influence, that is to say, how many guests come in $k1, and how many guests are displayed in $k2, which is called "tied on a rope" The grasshopper".

Difference

1. Difference in usage

The symbol passed by the value is =

quote The transfer symbol is &

2. The difference in meaning

Value transfer means that variables are transferred without affecting each other, while reference transfer means that two variables point to the same space. influencing each other.

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