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PHP调试中常用的几种输出方法

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Release: 2016-06-06 20:00:11
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PHP开发中,经常会查看变量的值,因此经常会将变量的值输出到页面以便于查看。 常用的输出方式有: echo 、 print 、 print_r 、 var_dump 、 var_exprot 等; echo和print常用来输出字符串; 查看数组常用print_r、var_dump、var_exprot; 若使用echo和prin

PHP开发中,经常会查看变量的值,因此经常会将变量的值输出到页面以便于查看。
常用的输出方式有:echoprintprint_rvar_dumpvar_exprot 等;
echo和print常用来输出字符串;
查看数组常用print_r、var_dump、var_exprot;
若使用echo和print输出数组时则,结果只能显示"Array",不会显示数组的结构。

一下举一例说明几种用法
配合print "

"和print "
Copy after login
",以数组$a为例说明各种输出的区别。
$a = array ('a' => 'apple', 'b' => 'banana', 'c' => array ('x', 'y', 'z'));

 

print_r($a);
输出结果:
Array ( [a] => apple [b] => banana [c] => Array ( [0] => x [1] => y [2] => z ) )

print "

"; print_r($a); print "
Copy after login
";
输出结果:
Array
(
    [a] => apple
    [b] => banana
    [c] => Array
        (
            [0] => x
            [1] => y
            [2] => z
        )

)

var_dump($a);
输出结果:
array(3) { ["a"]=>  string(5) "apple" ["b"]=>  string(6) "banana" ["c"]=>  array(3) { [0]=>  string(1) "x" [1]=>  string(1) "y" [2]=>  string(1) "z" } }

print "
"; var_dump($a); print "
Copy after login
";

输出结果:
array(3) {
  ["a"]=>
  string(5) "apple"
  ["b"]=>
  string(6) "banana"
  ["c"]=>
  array(3) {
    [0]=>
    string(1) "x"
    [1]=>
    string(1) "y"
    [2]=>
    string(1) "z"
  }
}

var_export($a);
输出结果:
array ( 'a' => 'apple', 'b' => 'banana', 'c' => array ( 0 => 'x', 1 => 'y', 2 => 'z', ), )

print "
"; var_export($a); print "
Copy after login
";

输出结果:
array (
  'a' => 'apple',
  'b' => 'banana',
  'c' =>
  array (
    0 => 'x',
    1 => 'y',
    2 => 'z',
  ),
)
调试的时候可以根据不同的需要选用不同的输出方式。

source:php.cn
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