--- 3 php interview topics, operator inspection point
A summary
Sentence summary:
Note that different logical operators shorting effect, priority issues directly brackets, && and || also noted with priority or and and
1, the difference between foo () and @foo ()?
@foo () error suppression
2, PHP operator error control character @?
PHP supports one error operator: @. When it is placed before a PHP expression, the expression of any possible error messages are ignored
3, php operator precedence?
Up / Down>! > Arithmetic Operators> Comparison of size> (no) is equal to Comparative> Reference> bitwise operator (^)> bitwise operator (|)> logic> logic or> trinocular> Assignment> and> xor> or
Brackets: Use parentheses to increase readability of the code can be recommended
4, php comparison operators test sites?
The difference between == and ===
Analyzing equivalent (FALSE case seven)
5, php increment / decrement operators pay attention to point?
A Boolean value: increment / decrement operators do not affect boolean values: true ++ or true; true-- still true
NULL: NULL value is not decreasing effect, incrementing a value of NULL
Increment decrement symbol locations: front to increment and decrement the first operator returns, otherwise return to the first, after the operation
6, php logical operator attention point?
A short circuit
&& and || or different and and and priority
Key memory increment / decrement operators rules of operation, the effect of short-circuiting logical operators, the logical operators to see more consideration to priority issues
7, interpreting the results of the following two expressions?
|||-begin
$a=false || true；→true $b=false or true；→false
|||-end
= || higher priority (number assignment)
priority less than or = (assignment number); the lowest priority logical operators in the English state
8, this expression ($ a = 3> 0 || $ b = 3> 0) of the order of execution is what?
1、(3>0)
2、(3>0||$b=3>0)
3, ($ a = (3> 0 || $ b = 3> 0)); $ b = 3> 0 is not implemented due to the short-circuit logic
Second, content in summary
Reproduced in: https: //www.cnblogs.com/Renyi-Fan/p/11058755.html