//Execute the external program or external instruction entered command. The returned string is just the last line returned after the external program is executed; if you need to return the information completely, you can use PassThru()
string exec(string command,string [array],int [return_var])
//Used to execute instructions and output results. If the return_var parameter exists, the status after executing command will be filled in return_var
string system(string command,int [return_var]
//Execute as an external program and display the original output
string passthru(string command,int [return_var])
//Remove special symbols in the string
string escapeshellcmd(string command)
//Used to lock files and enable other processes Unable to access. The parameter fp passed in is the file pointer. The value of the parameter operation is one of the following numbers: 1 means that the file is set to be locked to allow other processes to read; 2 means that only this process can write to the file; Indicates that both reading and writing are locked; 4 does not lock the file block (block)
bool flock(int fp,int operation)
//Extract all flag content attributes from the file and return a Array
array get_meta_tags(string filename[,int use_include_path])
//Read the entire file into an array, with each line as an array element
array file(void)
//Create a writable temporary file, which is automatically deleted when the fclose() function is called or the script ends
array tmpfile(void)
//Open a file or URL and return A file pointer
int fopen(string filename,string mode)
//Close an open file pointer
int fclose(int fp)
//Test a file pointer , see if it reaches the end of the file
int feof(int fp)
//Use the file pointer to get a line
string fgets(int fp,int length)
//Same as fgets () function, and at the same time remove the HTML language and PHP syntax mark characters in the retrieved string
string fgetss(int fp,int length)
//Get the character pointed to by the file pointer. If the pointer is in EOF, it returns false
string fgetc(int fp)
//Write the string string to the pointer fp of the file data stream. If length is specified, a string of the length will be written, or written to the end of the string
int fwrite(int fp,string string,int [lenth])
//Force to fp The pointed file enters the write operation
int fflush(int fp)
//Move the position of the file pointer to the beginning of the file
int rewind(int fp)
// Returns the pointer offset value of file fp. When an error occurs, return false
int ftell(int fp)
//Move the pointer of file fp to the specified offset (offset). When fp opens URL files such as http://... or ftp://... by fopen(), this function is invalid
int fseek(int fp,int offset)
/ /Read the file and write the file content to the standard output device
int readfile(string filename)
//Read the file fp until EOF and output the data to the standard output
int fpassthru(int fp)

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。

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。

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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mPDF is a PHP library that can generate PDF files from UTF-8 encoded HTML. The original author, Ian Back, wrote mPDF to output PDF files "on the fly" from his website and handle different languages. It is slower than original scripts like HTML2FPDF and produces larger files when using Unicode fonts, but supports CSS styles etc. and has a lot of enhancements. Supports almost all languages, including RTL (Arabic and Hebrew) and CJK (Chinese, Japanese and Korean). Supports nested block-level elements (such as P, DIV),
