一个函数对于标量参数可以定义c++-风格的默认值.
function makecoffee ($type = cappucino) {
echo making a cup of $type.;
}
echo makecoffee ();
echo makecoffee (espresso);
上面的程序段的输出如下:
making a cup of cappucino.
making a cup of espresso.
默认值必须是一个常量表达式,不是一个变量或类成员.
注意当时用默认参数时,任何默认都应该在任何非默认参数右边;否则,事情将不会想你所想的那样.考虑下面的程序段:
function makeyogurt ($type = acidophilus, $flavour) {
return making a bowl of $type $flavour.;
}
echo makeyogurt (raspberry); // 将不会按照预想工作
上面例子的输出是:
warning: missing argument 2 in call to makeyogurt() in
/usr/local/etc/httpd/htdocs/php3test/functest.html on line 41
making a bowl of raspberry .
现在,用下面的对比上面的:
function makeyogurt ($flavour, $type = acidophilus){
return making a bowl of $type $flavour.;
}
echo makeyogurt (“raspberry”);//正常工作
这个例子的输出是:
making a bowl of acidophilus raspberry.
http://www.bkjia.com/phpjc/531965.htmlwww.bkjia.comtruehttp://www.bkjia.com/phpjc/531965.htmltecharticle一个函数对于标量参数可以定义c++-风格的默认值. function makecoffee ($type = cappucino) { echo making a cup of $type.; } echo makecoffee (); echo makecoffee (espr...