Detailed explanation of php ternary operator

Today when I was revising my paper online, I came across a statement that I couldn’t understand:
$if_summary = $row['IF_SUMMARY']==2?'Yes':'No';
Later, Baidu found out that it was PHP's ternary operation. The meaning of this sentence is
if($row['IF_SUMMARY']==2){
$if_summary="Yes";
}else{
$if_summary="No";
}
三元The function of the operator is consistent with the "if...else" process statement. It is written in one line, and the code is very concise and the execution efficiency is higher.
Appropriate use of the ternary operator in PHP programs can make scripts 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 flow statements, you need to write multiple lines of code:
if(expr1) {
expr2;
} else {
expr3;
}
It can be seen that the ternary operator mentioned earlier is good 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 condition is true or not, the execution statement can be more than one sentence. Take a look at the following format:
(expr1) ? (expr2).(expr3) : (expr4).(expr5);
We can clearly see that multiple execution statements can be connected using the string operation symbol (".") , 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? $x=($aUse nested The ternary operator is not very readable, and there may be problems with maintaining the code in the future. However, compared with process statements such as "if...else", it is indeed too concise in the above situation. This is the allure of it.
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 you don't need to consider any "element" other than the conditional sentence in the "ternary", using the ternary operator is still more concise than if statements. The following statements are syntactically correct, they omit the second or third "element" in small dequotation marks:
$a>$b ? print "Yes" : "";
$a>$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:
$str = $_GET['abc'] ? 'wangjinbo' : 'wjb';
This cannot be understood as: when $str equals $_GET['abc'] , the assignment is 'wangjinbo' Otherwise, the value is 'wjb'; reason one: == should be used to judge equality; reason two: the syntax of the ternary operator is as shown above: (expr1) ? (expr2) : (expr3), obviously the above two Yuan, ternary 'wangjinbo' or 'wjb' alone cannot form a meaningful expression;
The correct understanding is: when $_GET['abc'] is empty (that is, whether, in PHP, '', null, 0, undifine, both are equivalent to Boolean value false), assign $str to 'wangjinbo', otherwise assign it to 'wjb';

Original link: bbs.php100.com/read-htm-tid-24239.html

The above has introduced a detailed explanation of the PHP ternary operator, including aspects of it. I hope it will be helpful to friends who are interested in PHP tutorials.