In this hour, you examined some of the functions that enable you to take control of the strings in your PHP scripts. You learned how to format strings with printf() and sprint(). You should be able to use these functions both to create strings that transform data and lay it out. You learned about functions that investigate strings. You should be able to discover the length of a string with strlen(), determine the presence of a substring with strpos(), or extract a substring with substr(). You should be able to tokenize a string with strtok().
You also learned about functions that transform strings. You can now remove whitespace from the beginning or end of a string with trim(), ltrim(), or rtrim(). You can change case with strtoupper(), strtolower(), or ucwords(). You can replace all instances of a string with str_replace().
After learning the PHP methods for string manipulation, you were introduced to MySQL functions that perform actions on strings. If you have strings in MySQL you want to concatenate or for which you want to count characters, you can use functions such as CONCAT(), CONCAT_WS(), and LENGTH(). To pad or remove padding from strings, use RPAD(), LPAD(), TRIM(), LTRIM(), and RRIM() to get just the strings you want. You can also find the location of a string within another, or to return a part of a given string, using the LOCATE(), SUBSTRING(), LEFT(), and RIGHT() functions. Functions such as LCASE(), UCASE(), REPEAT(), and REPLACE() also return variations of the original strings. MySQL also has numerous functions for representing strings, such as ASCII(), BIN(), OCT(), HEX(), and CONV() for converting between bases.