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    ▪php中根据变量的类型 选择echo或dump       此时，is_scalar内置函数就派上用场了。 is_scalar -- 检测变量是否是一个标量 标量变量是指那些包含了 integer、float、string 或 boolean的变量，而 array、object 和 resource 则不是标量。 代码如下: &l.........

    ▪PHP写的求多项式导数的函数代码       代码如下: <?php function getDerivativeByFormulaAndXDATA($formula, $x_data){ $xArray = explode("+", $formula); $Derivative = 0; foreach ($xArray as $x_record) { $tmpArray = explode("x^", $x_record); if(count($tmpArray) == 2){ $coefficient = $t.........

    ▪php中禁止单个IP与ip段访问的代码小结       禁止单个IP <?php //加IP访问限制 if(getenv('HTTP_CLIENT_IP') && strcasecmp(getenv('HTTP_CLIENT_IP'), 'unknown')) { $userip = getenv('HTTP_CLIENT_IP'); } elseif(getenv('HTTP_X_FORWARDED_FOR') && strcasecmp(getenv('HTTP_X_FO.........

代码如下:

<?php
function show_var($var) {
if (is_scalar($var)) {
echo $var;
} else {
var_dump($var);
}
}
$pi = 3.1416;
$proteins = array("hemoglobin", "cytochrome c oxidase", "ferredoxin");

show_var($pi);
// 打印：3.1416

show_var($proteins)
// 打印：
// array(3) {
// [0]=>
// string(10) "hemoglobin"
// [1]=>
// string(20) "cytochrome c oxidase"
// [2]=>
// string(10) "ferredoxin"
// }
?>

代码如下:

<?php
function getDerivativeByFormulaAndXDATA($formula, $x_data){
$xArray = explode("+", $formula);
$Derivative = 0;
foreach ($xArray as $x_record) {
$tmpArray = explode("x^", $x_record);
if(count($tmpArray) == 2){
$coefficient = $tmpArray[0]==""?1:$tmpArray[0];
$exp = $tmpArray[1];
}
//constant
else {
$coefficient = $tmpArray[0];
$exp = 0;
}
$Derivative += $coefficient*$exp*pow($x_data,$exp-1);
}
return $Derivative;
}
function getValueByFormulaAndXDATA($formula, $x_data){
$xArray = explode("+", $formula);
$y_data = 0;
foreach ($xArray as $x_record) {
$tmpArray = explode("x^", $x_record);
if(count($tmpArray) == 2){
$coefficient = $tmpArray[0]==""?1:$tmpArray[0];
$exp = $tmpArray[1];
}
//constant
else {
$coefficient = $tmpArray[0];
$exp = 0;
}
$y_data += $coefficient*pow($x_data,$exp);
}
return $y_data;
}
function getMaxDerivativeByFormulaAndXDATAS($formula, $x_datas, &$matchs){
$derivatives = array();
$max_derivative = 0;
foreach ($x_datas as $x_data) {
$derivative = getDerivativeByFormulaAndXDATA($formula, $x_data);
$derivatives[$x_data] = $derivative;
$max_derivative = $max_derivative>=abs($derivative)?$max_derivative:abs($derivative);
//printf("x=%f, derivative=%f \n",$x_data, $derivative);
}
$matchs = array();
foreach ($derivatives as $x_data=>$derivative) {
if(abs($derivative) == $max_derivative){
$matchs[] = $x_data;
}
}
printf("max derivative=%f\n",$max_derivative);
foreach ($matchs as $x_match) {
printf(" derivative=%f when x=%f\n",$derivatives[$x_match], $x_match);
}
}
//notice the format of formula: ax^b if b=0 could omit except coefficient a, if a=1 could omit coefficient
$formula = "x^2+2x^1+1";
print "The formula is $formula \n";
//printf("Derivative of 2 is %f \n",getDerivativeByFormulaAndXDATA($formula, 3.2));
//print getValueByFormulaAndXDATA($formula, 3.2)."\n";
$sampleData = array(-12,-11,-10,-9,-8,-7,-6,-5,-4,-3,-2,-1,1,2,3,4,5,6,7,8,9,10,11,12);
foreach ($sampleData as $x_data) {
$str.=$x_data.", ";
}
print "sample x values: $str \n";
getMaxDerivativeByFormulaAndXDATAS($formula, $sampleData, $matchs)."\n";
?>

代码如下:

<?php
//加IP访问限制
if(getenv('HTTP_CLIENT_IP') && strcasecmp(getenv('HTTP_CLIENT_IP'), 'unknown')) {
$userip = getenv('HTTP_CLIENT_IP');
} elseif(getenv('HTTP_X_FORWARDED_FOR') && strcasecmp(getenv('HTTP_X_FORWARDED_FOR'), 'unknown')) {
$userip = getenv('HTTP_X_FORWARDED_FOR');
} elseif(getenv('REMOTE_ADDR') && strcasecmp(getenv('REMOTE_ADDR'), 'unknown')) {
$userip = getenv('REMOTE_ADDR');
} elseif(isset($_SERVER['REMOTE_ADDR']) && $_SERVER['REMOTE_ADDR'] && strcasecmp($_SERVER['REMOTE_ADDR'], 'unknown')) {
$userip = $_SERVER['REMOTE_ADDR'];
}
$ban_range_low=ip2long("217.0.0.0"); //ip段上
$ban_range_up=ip2long("217.255.255.255");//ip段尾
$ip=ip2long($userip]);
if ($ip>$ban_range_low && $ip<$ban_range_up)
{
print "Banned";
exit();
}
?>