Checksums of various kinds are commonly used in data communication protocols to allow the recipient of a message to determine, quickly and easily, whether the data is likely to have been corrupted in transit. You'll find a wide array of checksum techniques in common use. Three of the most popular ones are the conventional checksum, LRC (longitudinal redundancy check), and CRC (cyclic redundancy check).
Getting a payment app up and running means being able to handle at least two different kinds of integration: First, you need to know how to integrate the necessary hardware (i.e., the card reader plus whatever it's plugged into); then you need to know how to integrate with a payment "back end," such as an online payment gateway (the party that "okays" the transaction and processes it for settlement).
Everybody knows what a pain in the "back end" chip cards can be. Insert your card, tap your foot, pray the chip misfires so you can go ahead and swipe... Okay, that might be overstating it. But you know what I mean. Standard "contact EMV" frustrates customers (and has driven many a payment-app developer to the brink of drink) because it's slow, complex, and unforgiving. All that changes with contactless EMV.
Muck Rack makes it simple to find people, tweets, or articles that mention any name, keyword, company, hashtag etc. We've compiled this guide to help you make the most of your search.
Selecting a term
Start searching tweets, articles from media outlets, articles mentioned in tweets, journalists'
names, titles and bios with some suggested searches:
Companies or Topics (e.g. iPhone, Microsoft)
Phrases (e.g. "cloud computing") — use quotes to keep the terms together
Twitter handles (e.g. @username) — returns those who have mentioned or replied to
Names (e.g. "David Pogue")
Hashtags (e.g. #sxsw, #london2012)
Bio details (e.g. vegan, Olympics, father)
Muck Rack's Advanced Search allows for many boolean operators.
Find results that mention multiple specified terms, use AND or
+. For example, ensure each result contains both Elon Musk and Mark Zuckerberg by
searching Obama AND Romney or Obama + Romney.
Use the operators OR or , to broaden your search when you'd like either of
multiple terms to appear in results. (This is the default behavior of our search when no operators
are used.) For example, search for democrat OR republican to find results that refer to
Democrats and/or Republicans.
Use NOT or - to subtract results from your search. For
example, searching Disney will yield results about the Walt Disney Company as well as Walt Disney
World Resort. To exclude mentions of Disney World, search for Disney -World or Disney
When using one of these operators with a phrase, enclose it in quotation marks. For example, you can
find results about smartphones excluding Apple's iPhone 4S by searching smartphone -"iPhone
Exact case matching or punctuation
If you're searching for a brand name or keyword that relies on specific punctuation marks or capitalization, you can
find results that match your exact query by adding matchcase: before the keyword you're searching for, like matchcase:E*TRADE .
Use parentheses to separate multiple
boolean phrases. For example, to find journalists talking about having fun in Disney World or
Disneyland, search for ("disney world" OR disneyland) AND fun.
An asterisk can be used to search for any variation of a root word truncated by the asterisk. For example, searching for admin* will return results for administrator, administration, administer, administered, etc.
A near operator is an AND operator where you can control the distance between the words. You can vary the distance the near operation uses by adding a forward slash and number (between 0-99) such as strawberries NEAR/10 "whipped cream", which means the strawberries must exist within 10 words of "whipped cream".