为什么无法输出一张图片

	session_start();		//随机码的个数	//$_rnd_code = 4;		//创建随机码	for($i=0;$i  
 输出结果为  
回复讨论(解决方案)
 
  $_nmsg='';  
 for($i=0;$i     $_nmsg.=dechex(mt_rand(0,15));  
 } 
 
  $_nmsg='';  
 for($i=0;$i     $_nmsg.=dechex(mt_rand(0,15));  
 }  
	session_start();		//随机码的个数	//$_rnd_code = 4;		$_nmsg=' ';	//创建随机码	for($i=0;$i  
 写完之后，还是显示  
  

Notice:  Undefined variable: _rnd_code in D:\AMP\web\ide_tmp.php on line 53

Warning:  Division by zero in D:\AMP\web\ide_tmp.php on line 53

Notice:  Undefined variable: _heght in D:\AMP\web\ide_tmp.php on line 53

Warning:  mt_rand(): max(0) is smaller than min(1) in D:\AMP\web\ide_tmp.php on line 53

Notice:  Undefined variable: _rnd_code in D:\AMP\web\ide_tmp.php on line 53

Warning:  Division by zero in D:\AMP\web\ide_tmp.php on line 53

Notice:  Undefined variable: _heght in D:\AMP\web\ide_tmp.php on line 53

Warning:  mt_rand(): max(0) is smaller than min(1) in D:\AMP\web\ide_tmp.php on line 53

Notice:  Undefined variable: _rnd_code in D:\AMP\web\ide_tmp.php on line 53

Warning:  Division by zero in D:\AMP\web\ide_tmp.php on line 53

Notice:  Undefined variable: _heght in D:\AMP\web\ide_tmp.php on line 53

Warning:  mt_rand(): max(0) is smaller than min(1) in D:\AMP\web\ide_tmp.php on line 53

Notice:  Undefined variable: _rnd_code in D:\AMP\web\ide_tmp.php on line 53

Warning:  Division by zero in D:\AMP\web\ide_tmp.php on line 53

Notice:  Undefined variable: _heght in D:\AMP\web\ide_tmp.php on line 53

Warning:  mt_rand(): max(0) is smaller than min(1) in D:\AMP\web\ide_tmp.php on line 53

Notice:  Undefined variable: _rnd_code in D:\AMP\web\ide_tmp.php on line 53

Warning:  Division by zero in D:\AMP\web\ide_tmp.php on line 53

Notice:  Undefined variable: _heght in D:\AMP\web\ide_tmp.php on line 53

Warning:  mt_rand(): max(0) is smaller than min(1) in D:\AMP\web\ide_tmp.php on line 53
‰PNG
按错误信息修改  
 然后得：  
 仍然是不友好的“验证码”图片  
  将header注释掉，打开错误就可以看到错误。