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This article introduces the relevant knowledge of "what is the basic knowledge of PHP". In the operation of actual cases, many people will encounter such a dilemma. Next, let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

The number of integers in php is signed and cannot be represented as unsigned integers. When the number of integers is out of range, it will be automatically converted from the number of integers to float. You can use the php_int_size constant to view the bytes occupied by the type of php integers, generally 4 bytes, so you can estimate the range of the number of integers, the highest number of symbols. You can also use the php_int_max constant to see the maximum value of int.

Small knowledge points:

1. When the variable is 0.0or "0" represents false in the Boolean variable

two。 String variables with double quotes in which variables and escape characters can be output normally according to their definition, while using single quotation marks to output content, it will output its contents as is, that is, escape characters or variables will not work, but will only output literal content as it is. You can write your own code to see the difference. Personally, the definition of the php variable is a bit similar to js, because you don't need to specify any type of it at all, and its type depends entirely on the type you actually use.

3. Arithmetic operator of php:

Note: the result obtained by dividing the sign "/" can be an integer or float. Instead of being just integers, for example, the result of 5Accord 2 is 2.5, while in C the result is 2. When the result is not divisible, the result displays 14 significant digits.

Operator one has five operators +, -, *, /, and%.

The symbol that connects two strings is not the + sign in java, but. Periods, periods will automatically treat the front and back variables as strings.

The difference between the "=" symbol and the "=" symbol:

The "=" symbol means that only the values on the left and right are equal.

The "= =" symbol means that not only the values on the left and right are equal, but even the variable types should be equal in order to return true.

The following example:

$axi2

$baked 2.0

In the above example, the values of the $an and $b variables are equal, but the types are not equal! All use = = is true, and use = = is false.

$a! = = $b means that the result is true as long as the values of an and b are not equal or the type is not equal.

$a! = $b means that only when the values of an and b are not equal, the result is true.

$a $b means the same meaning as $a! = $b.

The content of the output of echo $astub is not true or false. Instead, 0 and 1 stand for true,0 and 1 for false.

And > =,

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