Summary of usage of php ternary operator-PHP Tutorial-php.cn

Summary of usage of php ternary operator

巴扎黑

Release： 2023-03-14 18:28:01

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Ternary operator syntax: Condition ? Result 1: Result 2 Description: The position in front of the question mark is the condition for judgment. If the condition is met, the result is 1, and if it is not met, the result is 2. Let’s discuss this in detail below. Today when I was revising my paper online, I encountered a sentence that I couldn’t understand: $if_summary = $row['IF_SUMMARY']==2?'Yes':'No'; Later Baidu found out that it is the ternary operator of PHP The meaning of this sentence is equivalent to if($row['IF_SUMMARY']==2){ $if_summary= "Yes"; }else{ $if_summary="No"; } The function of the ternary operator is consistent with the "if...else" process statement. It is Written in one line, the code is very concise and the execution efficiency is higher. Appropriate use of the ternary operator in PHP programs can make the script more concise and efficient. The code format is as follows: (expr1) ? (expr2) : (expr3); Explanation: If the condition "expr1" is true, execute the statement "expr2", otherwise execute "expr3". To achieve the same function, if you use conditional process statements, you need to write multiple lines of code: if(expr1) { expr2; } else { expr3; } It can be seen that the goodness of the ternary operator mentioned above is not an exaggeration. However, in most cases we only use the ternary operator when the code is relatively simple, that is, when the execution statement is only a single sentence. For example: $a>$b ? print "a is greater than b" : print "a is less than b"; In fact, the ternary operator can be extended and used when the set conditions are met. Or not, the execution statement can be more than one sentence, try the following format: (expr1) ? (expr2).(expr3) : (expr4).(expr5); We are very obvious As you can see, multiple execution statements can be connected using string operators ("."), and each execution statement is surrounded by small angle brackets to indicate that it is an independent and complete execution statement. After this expansion, its function is closer to the "if...else" process statement. At the same time, the ternary operator can also be used nested. For example, when a is greater than b: if a is less than c, then x=c-a otherwise x=a-c; otherwise when a is less than b: if b is less than c, then x=c-b otherwise x=b-c: $ a>$b ? $x=($a<$c ? $c-$a : $a-$c) : $x=($b<$c ? $c-$b : $b-$c) ; The readability of the nested ternary operator is not very good, and there may be problems in maintaining the code in the future. However, compared with process statements such as "if...else", in the above In this case, it is indeed too simple, which is its attractiveness. For those who like to be lazy and pursue code simplicity, using the ternary operator to replace the if process statement should be an excellent choice. Even if there is no need to consider any "element" other than the conditional sentence in the "ternary", using the ternary operator is still more concise than the if statement. The syntax of the following statements is correct, they omit the second or third "element" in small dequotation marks: a>$b ? '': print 'No'; It should be noted that when using the ternary operator, it is recommended to use the print statement instead of the echo statement. Pay attention to the understanding of the following series of statements: ? 1 $str = $_GET['abc'] ? 'wangjinbo' : 'wjb'; This cannot be understood as: when $str is equal to $_GET['abc'], the assignment is 'wangjinbo' otherwise the assignment is 'wjb'; because one: == should be used to judge equality; reason two: ternary operator The syntax is as shown above: (expr1) ? (expr2) : (expr3). Obviously, the above binary and ternary 'wangjinbo' or 'wjb' cannot form a meaningful expression alone; The correct understanding is: when $_GET['abc'] is empty (that is, whether '', null, 0, undifine in PHP are all equivalent to the Boolean value false), assign $str to 'wangjinbo', otherwise assign a value for 'wjb';

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