Question

我在互联网上找到了一个非常有用的脚本。无论如何，我不希望它低于0.所以它不会显示负数。此外，我希望当数字增加时，它可以增加到一个值。例如，我不希望该数字超过20且小于0.

我该怎么做？

脚本就是这个

＆＃13;

<?php 
// gets current value 
if(isset($_POST['output'])){ 
    $value = $_POST['output']; 
} else { 
    $value = 0; 
} 
if($_POST['Add']){ 
    // opens the file for reading 
    $read = fopen("file.txt", 'r'); 
    // stores the file as variable cNumAdd 
    $cNumAdd = fread($read, 512); 
    // closes file 
    fclose($read); 
     
    // opens file again 
    $write = fopen("file.txt", "w+"); 
    // adds 1 to the data on the file 
    $cNumAdd = $cNumAdd + 1; 
    // writes the data into the file 
    fwrite($write, $cNumAdd); 
    // closes file 
    fclose($write); 
} 
// comments are the same as above except for subtracting 1 from file 
if($_POST['Remove']){ 
    $read = fopen("file.txt", 'r'); 
    $cNumRemove = fread($read, 512); 
    fclose($read); 
     
    $write = fopen("file.txt", "w+"); 
    $cNumRemove = $cNumRemove - 1; 
    fwrite($write, $cNumRemove); 
    fclose($write); 
} 
?> 


<form method="POST" action="<?php echo $_SERVER['PHP_SELF']; ?>">  
<input type="submit" name="Add" value="Add Career">  
<input type="submit" name="Remove" value="Remove Career">  
<input type="text" name="output" value="<?php include("file.txt"); ?> "> 
</form>

＆＃13;

Answer 1

您需要做的只是将数字与0和20进行比较。如果大于20，请手动将其设置为20.如果低于0，请手动将其设置为0.

示例：

$num = (int) $_REQUEST['output']; if ($num < 0) { $num = 0; } elseif ($num > 20) { $num = 20; }

Answer 2

我认为简单的IF语句可以削减它

＆＃13;

<?php 
// gets current value 
if(isset($_POST['output'])){ 
    $value = $_POST['output']; 
} else { 
    $value = 0; 
} 
//min and max definitions
define('MIN', 0);
define('MAX', 20);

if($_POST['Add']){ 
    // opens the file for reading 
    $read = fopen("file.txt", 'r'); 
    // stores the file as variable cNumAdd 
    $cNumAdd = fread($read, 512); 
    // closes file 
    fclose($read); 
    
    if($cNumAdd + 1 <= MAX){
    // opens file again 
    $write = fopen("file.txt", "w+"); 
    // adds 1 to the data on the file 
    $cNumAdd = $cNumAdd + 1; 
    // writes the data into the file 
    fwrite($write, $cNumAdd); 
    // closes file 
    fclose($write);
   }
} 
// comments are the same as above except for subtracting 1 from file 
if($_POST['Remove']){ 
    $read = fopen("file.txt", 'r'); 
    $cNumRemove = fread($read, 512); 
    fclose($read); 
    
    if($cNumRemove - 1 >= MIN){
    $write = fopen("file.txt", "w+"); 
    $cNumRemove = $cNumRemove - 1; 
    fwrite($write, $cNumRemove); 
    fclose($write);
    }
} 
?> 


<form method="POST" action="<?php echo $_SERVER['PHP_SELF']; ?>">  
<input type="submit" name="Add" value="Add Career">  
<input type="submit" name="Remove" value="Remove Career">  
<input type="text" name="output" value="<?php include("file.txt"); ?> "> 
</form>

＆＃13;

Answer 3

我希望这对你有用。

// opens file again 
$write = fopen("file.txt", "w+"); 
// adds 1 to the data on the file 
$cNumAdd = $cNumAdd + 1; 
// writes the data into the file 
if($cNumRemove > 20) $cNumRemove = 20;
fwrite($write, $cNumAdd); 
// closes file 
fclose($write); 
} 
// comments are the same as above except for subtracting 1 from file 
if($_POST['Remove']){ 
$read = fopen("file.txt", 'r'); 
$cNumRemove = fread($read, 512); 
fclose($read); 

$write = fopen("file.txt", "w+"); 
$cNumRemove = $cNumRemove - 1; 
if($cNumRemove < 0) $cNumRemove = 0;
fwrite($write, $cNumRemove); 
fclose($write); 
} 
?>

如何防止PHP脚本数值变为负数

3 个答案: