PHP中.=和+ =有什么区别? [英] What is the difference between .= and += in PHP?

问题描述

.=和+ =在PHP中有什么区别?

What are the differences between .= and += in PHP?

推荐答案

很简单，"+ ="是数字运算符，而.="是字符串运算符.考虑以下示例:

Quite simply, "+=" is a numeric operator and ".=" is a string operator. Consider this example:

$a = 'this is a ';
$a += 'test';

这就像写作:

$a = 'this' + 'test';

"+"或"+ ="运算符首先将值转换为整数(当转换为int时，所有字符串求值为零)，然后将它们相加，因此得到0.

The "+" or "+=" operator first converts the values to integers (and all strings evaluate to zero when cast to ints) and then adds them, so you get 0.

如果您这样做:

$a = 10;
$a .= 5;

这与写作相同:

$a = 10 . 5;

自." operator是一个字符串运算符，它首先将值转换为字符串；并且因为."表示连接"，结果是字符串"105".

Since the "." operator is a string operator, it first converts the values to strings; and since "." means "concatenate," the result is the string "105".

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