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如何使用复杂(卷曲)语法的常量?

curly-braces const php

5

aland · 技术社区 · 14 年前

我很惊讶地看到,下面的工作并不像预期的那样。

define('CONST_TEST','Some string');
echo "What is the value of {CONST_TEST} going to be?";

输出:{CONST\u TEST}的值是多少?

是的,我知道我可以

echo "What is the value of ".CONST_TEST." going to be?";

但我不希望合并字符串,与其说是为了性能,不如说是为了可读性。

4 回复 | 直到 14 年前

1

6

Sarfraz 14 年前

不,这是不可能的,因为php会考虑 CONST_TEST 只是在单引号/双引号内。你必须使用为了这个。

echo "What is the value of ".CONST_TEST." going to be?";

2

bcosca 14 年前

我不明白你为什么要大惊小怪,但你总是可以做到:

define('CONST_TEST','Some string');
$def=CONST_TEST;
echo "What is the value of $def going to be?";

3

1

Ruan Mendes 14 年前

define('CONST_TEST','Some string');
printf("What is the value of %s going to be?", CONST_TEST);

4

1

Hasta Dhana 5 年前

如果您非常想要这个特性,可以使用反射编写一段代码,查找所有常量及其值。然后将它们放入一个变量中,如 $CONSTANTS['CONSTANT_NAME']... $CONSTANTS

所以使用它看起来像:

$CONSTANTS = new constant_collection();

//this bit would normally be automatically populate using reflection to find all the constants... but just for demo purposes, here is what would and wouldn't be allowed.
$CONSTANTS['PI'] = 3.14;
$CONSTANTS['PI'] = 4.34; //triggers an error
unset($CONSTANTS['PI']); //triggers an error
foreach ($CONSTANTS as $name=>$value) {
    .... only if the correct interface methods are implemented to allow this
}
print count($CONSTANTS); //only if the countable interface is implemented to allow this

print "PI is {$CONSTANTS['PI']}"; //works fine :D

$C 而不是 $常量 ;)

希望有帮助,斯科特