我的代码：
SqlDependecy我希望myp可以打印得到的参数。 但它说 在./arg行17的字符串中使用未初始化的值$ _。
答案 0 :(得分：5)
Perl中子例程的参数在View.OnClickListener listener = new View.OnClickListener() {
@Override
public void onClick(View view) {
String[] facts = {
"Ants stretch when they wake up in the morning.",
"Ostriches can run faster than horses.",
"Olympic gold medals are actually made mostly of silver.",
"You are born with 300 bones; by the time you are an adult you will have 206.",
"It takes about 8 minutes for light from the Sun to reach Earth.",
"Some bamboo plants can grow almost a meter in just one day.",
"The state of Florida is bigger than England.",
"Some penguins can leap 2-3 meters out of the water.",
"On average, it takes 66 days to form a new habit.",
"Mammoths still walked the earth when the Great Pyramid was being built." };
String fact = "";
for(int i=0;i<facts.length;i++)
{
fact+=facts[i];
}
funFactTextView.setText(fact);//set the new string
}
};
buttonFact.setOnClickListener(listener);//button clicked updates new string
数组中传递。这与@_变量不同。
一个常见的习惯用法是在函数的第一行中“解压缩”这些参数，例如
$_还可以将参数直接引用为sub example {
my ($arg1, $arg2) = @_;
print "$arg1 and $arg2";
}
的元素，例如就像@_一样，但这很难阅读，因此最好避免。
答案 1 :(得分：1)
我通常会做类似的事情：
my $first_arg = shift @_;
my $second_arg = shift @_;
您还可以使用其他响应的方法：
my ($first_arg, $second_arg) = @_;
但是要小心地说：
my $first_arg = @_;
因为您将获得传递给子例程的参数数量。
在引用$_时，您引用的是默认字符串变量，在这种情况下，您可能希望引用@_，如果要获取特定的参数，则必须说{{1} }，如果这样做，请小心将数组传递给子例程：
$_[narg]您将传递整个数组，因为它是参数列表，相反，您应该说：
some_sub(@myarray);