PHP Developer’s Dictionary IT-SC book 180 in haystack , the function returns false. Only the first character of needle will be used, and if needle is a number, its corresponding ASCII value is used. echo strrchr ("abcdefg","d123");//displays defg str_repeat() Syntax string str_repeat(string input, int multiplier) Description The str_repeat() function, which was added in PHP 4.0b4, returns the input string repeated the number of times indicated by multiplier . The multiplier parameter must be greater than 0. echo str_repeat("*",50);//displays 50 asterisks strrev() Syntax string strrev(string string) Description The strrev() function returns the string in reverse order. strrpos() Syntax int strrpos(string haystack, char needle) Description PHP Developer’s Dictionary IT-SC book 181 The strrpos() function returns the numeric position of the last occurrence of needle in the string haystack . Note that needle is a character and, if passed in as a string, only the first character will be used. If needle is not a string, it is converted to an integer and applied as the ordinal value of a character. If needle is not found in haystack , false is returned. $text = "123456"; echo strpos ($text,"4");//displays 3 strspn() Syntax int strspn(string str1, string str2) Description The strspn() function, which was added in PHP 3.0.3 and PHP 4.0, returns the length of the initial segment of str1 , which consists of characters found only in str2 . strstr() Syntax string strstr(string haystack, string needle) Description The strstr() function returns a portion of haystack starting from the first occurrence of needle to the end of haystack . If needle is not found, false is returned. If needle is not a string, it is converted to an integer and applied as the ordinal value of a character. strtok() Syntax string strtok(string arg1, string arg2) Description PHP Developer’s Dictionary IT-SC book 182 The strtok() function is used to tokenize a string into smaller pieces. arg1 indicates the string to be tokenized and arg2 is the field separator to use for tokenizing the string. If arg2 consists of more than one character, any of the characters found will create a token. An internal pointer is kept between calls of strtok() . To continue tokenizing the same string, you should specify only the separator string and not the original string each time. $connstr = "UID=USER;PWD=PASSWD"; strtok ($connstr,"="); $userid = strtok (";"); strtok ("="); $password = strtok (";"); echo $userid."/".$password;//displays USER/PASSWORD strtolower() Syntax string strtolower(string str) Description The strtolower() function returns str with all alphabetic characters converted to lowercase. Note that the alphabet is determined by the current locale setting. strtoupper() Syntax string strtoupper(string string) Description The strtoupper() function returns string with all alphabetic characters converted to uppercase. Note that the alphabet is determined by the current locale setting. str_replace() Syntax string str_replace(string needle, string str, string haystack) PHP Developer’s Dictionary IT-SC book 183 Description The str_replace() function, which was added in PHP 3.0.6 and PHP 4.0, returns a string in which all occurrences of needle in haystack have been replaced by str . This is a simplified version of ereg_replace() and is the preferred function when possible. echo str_replace("1","2","1212");//displays 2222 strtr() Syntax string strtr(string str, string from, string to) Description The strtr() function examines str , replaces all occurrences of each character in from with the corresponding character in to , and returns the resulting string. The from and to parameters should be the same length and if not, the extra characters are ignored. strtr() can also be called with only two parameters. In this case, from should be an array that contains string -> string pairs that indicate what should be replaced in str . Note that strtr() always looks for the longest possible match first and doesn't work recursively. This two-argument functionality was added in PHP 4.0. echo strtr ("a1b1c1","1","2");//displays a2b2c2 substr() Syntax string substring(string string, int start, int [length]) Description The substr() function returns the portion of string specified by the start and optional length parameters. A positive value of start indicates the offset at which PHP Developer’s Dictionary IT-SC book 184 to start searching string is from the beginning, and a negative value of start indicates that the offset at which to start searching is from the end of string . If the optional parameter length is positive, the string returned will end length characters from start . If this will result in a string with negative length (because the start is past the end of the string), the returned string will contain the single character at start . If the optional parameter length is negative, the string returned will end length characters from the end of string . If this will result in a string with negative length, the returned string will contain the single character at start . echo substr("12345",1,3);//displays 234 substr_replace() Syntax string substr_replace(string string, string replacement, int start, int [length]) Description The substr_replace() function, which was added in PHP 4.0b4, replaces the part of string bounded by the start and (optional) length parameters with the replacement string and returns the result. If start is positive, the replacement starts at the start location in the string . If start is negative, the replacement begins at the position start number of characters from the end of string . When the optional parameter length is positive, it represents the length of the amount of string that should be replaced. When length is negative, it represents the position from the end of string at which to stop replacing. If length is not given, the whole length of string is used. echo substr_replace ("12345","432",2,3);//displays 12432 trim() Syntax string trim(string str) Description . needle, string str, string haystack) PHP Developer’s Dictionary IT-SC book 183 Description The str_replace() function, which was added in PHP 3.0.6 and PHP 4.0, returns a string in which. strspn(string str1, string str2) Description The strspn() function, which was added in PHP 3.0.3 and PHP 4.0, returns the length of the initial segment of str1 , which consists of characters. reverse order. strrpos() Syntax int strrpos(string haystack, char needle) Description PHP Developer’s Dictionary IT-SC book 181 The strrpos() function returns the numeric position