php 如何删除字段

void unset ( mixed $var [, mixed $... ] )

<?php
// 销毁单个变量
unset ($foo);
 
// 销毁单个数组元素
unset ($bar[&#39;quux&#39;]);
 
// 销毁一个以上的变量
unset($foo1, $foo2, $foo3);
?>

<?php
function destroy_foo() {
    global $foo;
    unset($foo);
}
 
$foo = &#39;bar&#39;;
destroy_foo();
echo $foo;
?>

bar

<?php
function foo() 
{
    unset($GLOBALS[&#39;bar&#39;]);
}
 
$bar = "something";
foo();
?>

<?php
function foo(&$bar) {
    unset($bar);
    $bar = "blah";
}
 
$bar = &#39;something&#39;;
echo "$bar\n";
 
foo($bar);
echo "$bar\n";
?>

something
something

<?php
function foo()
{
    static $bar;
    $bar++;
    echo "Before unset: $bar, ";
    unset($bar);
    $bar = 23;
    echo "after unset: $bar\n";
}
 
foo();
foo();
foo();
?>

Before unset: 1, after unset: 23
Before unset: 2, after unset: 23
Before unset: 3, after unset: 23