In order to prevent some people from uploading executable files such as exe to the server, we can write a program to determine the type of the uploaded file, and then files that do not meet the type will be refused to upload.
The following is the PHP program that implements this function:
function ($file_name, $pass_type = array('jpg','jpeg','gif','bmp','png') ) { // 允许文件类型的后缀组成的数组 $file = $pass_type; // 截取上传文件的文件名的后缀 $kzm = substr(strrchr($file_name,"."),1); // 判断此后缀是否在数组中 $is_img = in_array(strtolower($kzm),$file); if($is_img) { return true; } else { return false; } }
in_array() function
in_array() function searches an array for a given value. Usage: in_array(value,array,type).
- Parameter value, required. Specifies the value to search for in the array.
- Parameter array, required. Specifies the array to search.
- Parameter type, optional. If this parameter is set to true, it is checked whether the type of the searched data and the value of the array are the same.
Returns true if the given value value exists in the array array. If the third parameter is set to true, the function returns true only if the element exists in the array and has the same data type as the given value.
If the parameter is not found in the array, the function returns false.
If the value parameter is a string and the type parameter is set to true, the search is case-sensitive.
<?php $people = array("Peter", "Joe", "Glenn", "Cleveland"); if (in_array("Glenn",$people)) { echo "Match found"; } else { echo "Match not found"; } ?>
Program output:
Match found
Another sample program:
<?php $people = array("Peter", "Joe", "Glenn", "Cleveland", 23); if (in_array("23",$people, TRUE)) { echo "Match found<br />"; } else { echo "Match not found<br />"; } if (in_array("Glenn",$people, TRUE)) { echo "Match found<br />"; } else { echo "Match not found<br />"; } if (in_array(23,$people, TRUE)) { echo "Match found<br />"; } else { echo "Match not found<br />"; } ?>
Program output:
Match not found Match found Match found

php把负数转为正整数的方法:1、使用abs()函数将负数转为正数,使用intval()函数对正数取整,转为正整数,语法“intval(abs($number))”;2、利用“~”位运算符将负数取反加一,语法“~$number + 1”。

实现方法:1、使用“sleep(延迟秒数)”语句,可延迟执行函数若干秒;2、使用“time_nanosleep(延迟秒数,延迟纳秒数)”语句,可延迟执行函数若干秒和纳秒;3、使用“time_sleep_until(time()+7)”语句。

php除以100保留两位小数的方法:1、利用“/”运算符进行除法运算,语法“数值 / 100”;2、使用“number_format(除法结果, 2)”或“sprintf("%.2f",除法结果)”语句进行四舍五入的处理值,并保留两位小数。

php字符串有下标。在PHP中,下标不仅可以应用于数组和对象,还可应用于字符串,利用字符串的下标和中括号“[]”可以访问指定索引位置的字符,并对该字符进行读写,语法“字符串名[下标值]”;字符串的下标值(索引值)只能是整数类型,起始值为0。

判断方法:1、使用“strtotime("年-月-日")”语句将给定的年月日转换为时间戳格式;2、用“date("z",时间戳)+1”语句计算指定时间戳是一年的第几天。date()返回的天数是从0开始计算的,因此真实天数需要在此基础上加1。

在php中,可以使用substr()函数来读取字符串后几个字符,只需要将该函数的第二个参数设置为负值,第三个参数省略即可;语法为“substr(字符串,-n)”,表示读取从字符串结尾处向前数第n个字符开始,直到字符串结尾的全部字符。

方法:1、用“str_replace(" ","其他字符",$str)”语句,可将nbsp符替换为其他字符;2、用“preg_replace("/(\s|\ \;||\xc2\xa0)/","其他字符",$str)”语句。

查找方法:1、用strpos(),语法“strpos("字符串值","查找子串")+1”;2、用stripos(),语法“strpos("字符串值","查找子串")+1”。因为字符串是从0开始计数的,因此两个函数获取的位置需要进行加1处理。


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