前言
昨晚實驗室一師弟在微薄上@我,給我發了幾道php的基礎面試題,這裡把我寫的答案貼出來
題目
(1)寫一個函數獲取URL的文件後綴,例如“http://www.feiyan.info/test.php?c=class&m=method”(獲得php或者.php)
[php]
<?php
/**
* 給定url,獲取文件後綴
* @param string $url
* @return string
*/
function getUrlPostfix ($url)
{
$url_arr = explode('.', $url);
$postfix = $url_arr[count($url_arr) - 1];
$substr = substr($postfix, 0, 3);
return $substr;
}
$url = "http://www.feiyan.info/test.php?c=class&m=method";
$str = getUrlPostfix($url);
echo $str . "\n";
<?php
/**
* 給定url,獲取文件後綴
* @param string $url
* @return string
*/
function getUrlPostfix ($url)
{
$url_arr = explode('.', $url);
$postfix = $url_arr[count($url_arr) - 1];
$substr = substr($postfix, 0, 3);
return $substr;
}
$url = "http://www.feiyan.info/test.php?c=class&m=method";
$str = getUrlPostfix($url);
echo $str . "\n";
(2)寫一個函數,將一個字符串每隔三個字符添加一個逗號,例如把字符串1234567890轉換為1,234,567,890(金融中用到的記賬方法)
[php]
<?php
/**
* 每隔3個字符,用逗號進行分隔
* @param string $str
* @return string
*/
function splitStrWithComma ($str)
{
$arr = array();
$len = strlen($str);
for ($i = $len - 1; $i >= 0;) {
$new_str = "";
for ($j = $i; $j > $i - 3 && $j >= 0; $j --) {
$new_str .= $str[$j];
}
$arr[] = $new_str;
$i = $j;
}
$string = implode(',', $arr);
// 翻轉字符串自己實現
// $string = strrev($string);
for ($i = 0, $j = strlen($string) - 1; $i <= $j; $i ++, $j --) {
$tmp = $string[$i];
$string[$i] = $string[$j];
$string[$j] = $tmp;
}
return $string;
}
$str = "1234567890";
$new_str = splitStrWithComma($str);
echo $new_str . "\n";
<?php
/**
* 每隔3個字符,用逗號進行分隔
* @param string $str
* @return string
*/
function splitStrWithComma ($str)
{
$arr = array();
$len = strlen($str);
for ($i = $len - 1; $i >= 0;) {
$new_str = "";
for ($j = $i; $j > $i - 3 && $j >= 0; $j --) {
$new_str .= $str[$j];
}
$arr[] = $new_str;
$i = $j;
}
$string = implode(',', $arr);
// 翻轉字符串自己實現
// $string = strrev($string);
for ($i = 0, $j = strlen($string) - 1; $i <= $j; $i ++, $j --) {
$tmp = $string[$i];
$string[$i] = $string[$j];
$string[$j] = $tmp;
}
return $string;
}
$str = "1234567890";
$new_str = splitStrWithComma($str);
echo $new_str . "\n";
(3)寫一個php函數算出兩個文件的相對路徑。例如$a="/a/b/c/d/e.php"; $b="/a/b/12/34/c.php",B相對於A的相對路徑是什麼?
這道題目可以看成是求第一個公共節點的題目,網上流傳的代碼大部分是錯的,考慮不周全,當然我這個也只是用“../”去表示,沒用"./"
[php]
<?php
/**
* 求$b相對於$a的相對路徑
* @param string $a
* @param string $b
* @return string
*/
function getRelativePath ($a, $b)
{
$patha = explode('/', $a);
$pathb = explode('/', $b);
$counta = count($patha) - 1;
$countb = count($pathb) - 1;
$path = "../";
if ($countb > $counta) {
while ($countb > $counta) {
$path .= "../";
$countb --;
}
}
// 尋找第一個公共結點
for ($i = $countb - 1; $i >= 0;) {
if ($patha[$i] != $pathb[$i]) {
$path .= "../";
$i --;
} else { // 判斷是否為真正的第一個公共結點,防止出現子目錄重名情況
for ($j = $i - 1, $flag = 1; $j >= 0; $j --) {
if ($patha[$j] == $pathb[$j]) {
continue;
} else {
$flag = 0;
break;
}
}
if ($flag)
break;
else
$i ++;
}
}
for ($i += 1; $i <= $counta; $i ++) {
$path .= $patha[$i] . "/";
}
return $path;
}
$a = "/a/c/d/e.php";
$b = "/a/c.php";
$path = getRelativePath($a, $b);
echo $path;
<?php
/**
* 求$b相對於$a的相對路徑
* @param string $a
* @param string $b
* @return string
*/
function getRelativePath ($a, $b)
{
$patha = explode('/', $a);
$pathb = explode('/', $b);
$counta = count($patha) - 1;
$countb = count($pathb) - 1;
$path = "../";
if ($countb > $counta) {
while ($countb > $counta) {
$path .= "../";
$countb --;
}
}
// 尋找第一個公共結點
for ($i = $countb - 1; $i >= 0;) {
if ($patha[$i] != $pathb[$i]) {
$path .= "../";
$i --;
} else { // 判斷是否為真正的第一個公共結點,防止出現子目錄重名情況
for ($j = $i - 1, $flag = 1; $j >= 0; $j --) {
if ($patha[$j] == $pathb[$j]) {
continue;
} else {
$flag = 0;
break;
}
}
if ($flag)
break;
else
$i ++;
}
}
for ($i += 1; $i <= $counta; $i ++) {
$path .= $patha[$i] . "/";
}
return $path;
}
$a = "/a/c/d/e.php";
$b = "/a/c.php";
$path = getRelativePath($a, $b);
echo $path;
(4)計算兩個日期之間的天數
[php]
<?php
/**
* 求兩個日期之間相差的天數(針對1970年1月1日之後,求之前可以采用泰勒公式)
* @param string $day1
* @param string $day2
* @return number
*/
function diffBetweenTwoDays ($day1, $day2)
{
$second1 = strtotime($day1);
$second2 = strtotime($day2);
if ($second1 < $second2) {
$tmp = $second2;
$second2 = $second1;
$second1 = $tmp;
}
return ($second1 - $second2) / 86400;
}
$day1 = "2013-07-27";
$day2 = "2013-08-04";
$diff = diffBetweenTwoDays($day1, $day2);
echo $diff."\n";
<?php
/**
* 求兩個日期之間相差的天數(針對1970年1月1日之後,求之前可以采用泰勒公式)
* @param string $day1
* @param string $day2
* @return number
*/
function diffBetweenTwoDays ($day1, $day2)
{
$second1 = strtotime($day1);
$second2 = strtotime($day2);
if ($second1 < $second2) {
$tmp = $second2;
$second2 = $second1;
$second1 = $tmp;
}
return ($second1 - $second2) / 86400;
}
$day1 = "2013-07-27";
$day2 = "2013-08-04";
$diff = diffBetweenTwoDays($day1, $day2);
echo $diff."\n";