Coding

By mkyong – November 18, 2009

Regular expression is an art of the programing, it’s hard to debug , learn and understand, but the powerful features are still attract many developers to code regular expression. Let’s explore the following 10 practical regular expression ~ enjoy 🙂

1. Username Regular Expression Pattern

^[a–z0–9_–]{3,15}$

^ # Start of the line

[a–z0–9_–] # Match characters and symbols in the list, a-z, 0-9 , underscore , hyphen

{3,15} # Length at least 3 characters and maximum length of 15

$ # End of the line Continue reading “10 Java Regular Expression Examples You Should Know”

How much do context switches matter?

By Marc Brooker

Years ago, while taking a numerical methods course, I wrote some code to calculate the expected number of shared birthdays in a group. The code is very simple: each attempt constructs a vector of N birthdays, then counts the duplicates. The outer loop runs millions of attempts, and calculates the mean number of shared birthdays across all the samples. It’s little more than a tight loop around a pseudo-random number generator. Continue reading “Make Your Program Slower With Threads”

1. Username Regular Expression Pattern

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How much do context switches matter?

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