php - 变量中的变量

Question

由于某种原因，我似乎无法解决这个问题。

$welcome_message = "Hello there $name";

$names_array = array("tom", "dick", "harry");

foreach ($names_array as $this_name) {
    $name = $this_name;
    echo $welcome_message."<br>";
}

如何每次更新 $welcome_message 中的 $name 变量？

使用可变变量，但我似乎无法使其工作。

谢谢

Answer 1

也许你正在寻找sprintf？

$welcome_message = "Hello there %s";

$names_array = array("tom", "dick", "harry");

foreach ($names_array as $this_name) {
    echo sprintf($welcome_message, $this_name), "<br>";
}

Answer 2

这不起作用，因为$welcome_message在开始时只评估一次（何时$name可能仍未定义）。您不能在内部“保存”所需的表单$welcome_message并在以后随意“扩展”它（除非您使用eval，这是完全避免的事情）。

移动设置$welcome_message在循环内的行：

$names_array = array("tom", "dick", "harry");

foreach ($names_array as $this_name) {
    $welcome_message = "Hello there $this_name";
    echo $welcome_message."<br>";
}

Answer 3

你可以像这样每次更新 $welcome_message....

$welcome_message = "Hello there ".$name;

现在代码将是这样的......

$welcome_message = "Hello there ";

$names_array = array("tom", "dick", "harry");

foreach ($names_array as $this_name) {
echo $welcome_message.$this_name"<br>";
}