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I noticed that some functions in PHP use flags as arguments. What makes them unique instead of plain string arguments? I'm asking since I want to use them on my own custom functions but am curious as to what the process is for doing so.
Edit: TO summarize, when is it best to create a custom function with flags and when is it not?
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The ArrayObject::setFlags() function is an inbuilt function in PHP which is used to set the flag to change the behavior of the ArrayObject. Syntax: void ArrayObject::setFlags( int $flags ) Parameters: This function accepts single parameter $flags which holds the behavior of new ArrayObject.
PHP Function ArgumentsAn argument is just like a variable. Arguments are specified after the function name, inside the parentheses. You can add as many arguments as you want, just separate them with a comma. The following example has a function with one argument ($fname).
PHP allows us to set default argument values for function parameters. If we do not pass any argument for a parameter with default value then PHP will use the default set value for this parameter in the function call. Example: PHP.
By default, function arguments are passed by value (so that if the value of the argument within the function is changed, it does not get changed outside of the function). To allow a function to modify its arguments, they must be passed by reference.
Usually flags are integers that are consecutive powers of 2, so that each has one bit set to 1 and all others to 0. This way you can pass many binary values in a single integer using bit-wise operators. See this for more (and probably more accurate) information.
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They are just constants which map to a number, e.g. SORT_NUMERIC (a constant used by sorting functions) is the integer 1.
Check out the examples for json_encode().
As you can see, each flag is 2n. This way, | can be used to specify multiple flags.
For example, suppose you want to use the flag JSON_FORCE_OBJECT (16 or 00010000) and JSON_PRETTY_PRINT (128 or 10000000).
The bitwise operator OR (|) will turn the bit on if either operand's bit is on...
JSON_FORCE_OBJECT | JSON_PRETTY_PRINT
...is internally....
00010000 | 1000000
...which is...
10010000
You can check it with...
var_dump(base_convert(JSON_PRETTY_PRINT | JSON_FORCE_OBJECT, 10, 2));
// string(8) "10010000"
CodePad.
This is how both flags can be set with bitwise operators.
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