Definition and processing of strings

\ N carriage return \ r line feed \ t carriage return 1. definition: Double quotation marks: A. variables can be executed in double quotation marks, for example, $ num = 1000; $ STR = "It is my $ num life"; echo $ STR; in this case, it is output "My 1000 life", indicating that variables can be identified in double quotation marks. However, if you want to execute the above method normally, add a space before and after the variable, write the variable as $ {num}, or use it according to the rules in PHP ". "will be connected before and after. B. You can use the Escape Character $ STR = "This Is A \" string \ "test"; defined in single quotes: a. Variable B cannot be executed in single quotes. only partial escape characters can be used. escape characters can be used before single quotes. The "\" character can be used to escape the characters defined by anti-quotation marks: $ STR = 'aaaaaaaaa'; // No error occurs, but the server command is not output in the backquotes. If the server is Linux, the Linux command can be used, for Windows, it can be a Windows command, for example, $ STR = "ipconifg/all"; echo $ STR; the delimiter defines: "<", $ STR =

$ Pos1 = strrpos ($ URL, "/") + 1;

$ STR = substr ($ URL, $ pos1 );

$ Pos2 = strpos ($ STR ,"? ");

$ STR = substr ($ STR, 0, $ pos2 );

Echo $ STR; Output demo. php

Str_pad (the string to be processed, the length of the string after processing, the string to be filled, and the direction to fill): String filling function,

The fourth parameter has three constants: str_pad_left, left filled

Str_pad_right: Fill on the right

Str_pad_both: Fill both sides

$ STR = "www.baidu.com"; $ str2 = str_pad ($ STR, 30, "#", str_pad_left); string comparison: String comparison by byte strcmp () strcasecmp () compare the fuzzy comparison of strnatcmp () strings by natural sorting without case sensitivity soundex () returns the number of matching str_replace (string str1, string str2, string str2, string str3) replace str1 in str3 with str2 str_replace (array arr, string str2, string str3) str_replace (array arr1, array arr2, string str3) strtr (string STR, string from, string to) string translation function, which replaces strtr (string STR, array ARR) $ STR = "http://www.baidu.com "; $ arr = array ("HTTP"-> "ftp", "Baidu"-> "google"); $ newstr = strtr ($ STR, $ ARR); stripslashes () remove the Escape Character addslashes () htmlentities () for processing HTML tags htmlspecialchars () strip_tags () Forcibly Delete the HTML Tag strip_tags (STR, tags ): strip_tags ("<B> DD </B>", "<B> <I>") This Code indicates that, other functions such as parse_str () parse_url () URL encoding handler: rawurlencode (); urlencode () urldecode () to construct query strings: http_build_query ();