CONTENTS

• NAME
• DESCRIPTION
• Data: Numbers
  • Why am I getting long decimals (eg, 19.9499999999999) instead of the numbers I should be getting (eg, 19.95)?
  • Why is int() broken?
  • Why isn't my octal data interpreted correctly?
  • Does Perl have a round() function? What about ceil() and floor()? Trig functions?
  • How do I convert between numeric representations/bases/radixes?
  • Why doesn't & work the way I want it to?
  • How do I multiply matrices?
  • How do I perform an operation on a series of integers?
  • How can I output Roman numerals?
  • Why aren't my random numbers random?
  • How do I get a random number between X and Y?
• Data: Dates
  • How do I find the day or week of the year?
  • How do I find the current century or millennium?
  • How can I compare two dates and find the difference?
  • How can I take a string and turn it into epoch seconds?
  • How can I find the Julian Day?
  • How do I find yesterday's date?
  • Does Perl have a Year 2000 problem? Is Perl Y2K compliant?
• Data: Strings
  • How do I validate input?
  • How do I unescape a string?
  • How do I remove consecutive pairs of characters?
  • How do I expand function calls in a string?
  • How do I find matching/nesting anything?
  • How do I reverse a string?
  • How do I expand tabs in a string?
  • How do I reformat a paragraph?
  • How can I access or change N characters of a string?
  • How do I change the Nth occurrence of something?
  • How can I count the number of occurrences of a substring within a string?
  • How do I capitalize all the words on one line?
  • How can I split a [character] delimited string except when inside [character]?
  • How do I strip blank space from the beginning/end of a string?
  • How do I pad a string with blanks or pad a number with zeroes?
  • How do I extract selected columns from a string?
  • How do I find the soundex value of a string?
  • How can I expand variables in text strings?
  • What's wrong with always quoting "$vars"?
  • Why don't my <<HERE documents work?
• Data: Arrays
  • What is the difference between a list and an array?
  • What is the difference between $array[1] and @array[1]?
  • How can I remove duplicate elements from a list or array?
  • How can I tell whether a certain element is contained in a list or array?
  • How do I compute the difference of two arrays? How do I compute the intersection of two arrays?
  • How do I test whether two arrays or hashes are equal?
  • How do I find the first array element for which a condition is true?
  • How do I handle linked lists?
  • How do I handle circular lists?
  • How do I shuffle an array randomly?
  • How do I process/modify each element of an array?
  • How do I select a random element from an array?
  • How do I permute N elements of a list?
  • How do I sort an array by (anything)?
  • How do I manipulate arrays of bits?
  • Why does defined() return true on empty arrays and hashes?
• Data: Hashes (Associative Arrays)
  • How do I process an entire hash?
  • What happens if I add or remove keys from a hash while iterating over it?
  • How do I look up a hash element by value?
  • How can I know how many entries are in a hash?
  • How do I sort a hash (optionally by value instead of key)?
  • How can I always keep my hash sorted?
  • What's the difference between "delete" and "undef" with hashes?
  • Why don't my tied hashes make the defined/exists distinction?
  • How do I reset an each() operation part-way through?
  • How can I get the unique keys from two hashes?
  • How can I store a multidimensional array in a DBM file?