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Square Cash 有 pro version 了

Square Cash 有 pro version 了# Money - 海外理财

w*g2015-04-16 07:04

1 楼

都是C++的题：
怎么找memory leak
我回答有现成的工具但我没用过。也可以自己写个计数器记录new/delete/malloc/free
的次数，在runtime边运行边记录。他追问：整个project就一个计数器吗？我回答每个
class一个计数器。不知对错。
TCP和UDP的区别
STL里map和hashmap的区别
什么是纯虚函数
如果父类有一个纯虚函数，子类却没有覆盖这个纯虚函数，那么子类对象调用这个函数
时会怎样？
逻辑题：有三个桶，一个只装白球，一个只装黑球，一个黑白都装。有三个标签，一个
写着“白”，一个写着“黑”，一个写着“混合”。三个标签全都贴错了。
问最少需要拿出几个球才能知道每个桶到底装了什么？
我回答一个。

m*22015-04-16 07:04

2 楼

Five years ago, Square introduced a sleek card reader to the small-business
world that made it easy for everyone from taxi drivers to craft sellers to
coffee shop owners to accept credit card payments for the first time. On
Monday, Square is unveiling another card processing service that it believes
will allow even more entrepreneurs, artists and business owners to ditch
cash and check payments for card payments.
The new service is an extension of the Square Cash payment system that
Square launched in 2013. That service lets individuals transfer money to
another person via email or the Square Cash app through a link to a debit
card. Now, small businesses, artists and nonprofits can start receiving
debit payments via the Square Cash payment system, too, as Square attempts
to increase the volume of payments it processes, which makes up the vast
majority of its revenue.
Here’s how it’ll work. Starting Monday, any individual, business or
nonprofit can create a Square Cash username — or $cashtag, in Square
parlance — that consists of a dollar sign followed by a name, such as $
DelRey. With that username, a person or business can automatically set up a
simple payment page at https://cash.me. Mine, for example, is cash.me/$
DelRey.
When visitors land on that page, they are greeted with a big box to enter a
dollar amount for a payment. Next, they enter a debit card number,
expiration date, the CVV code on the back of the card, and ZIP code. If they
haven’t previously signed up for Square Cash, they’ll also enter their
name and phone number or email address to activate a new account and receive
an email receipt of their transaction. Payment complete. (If you really
want to try it out, my cash.me page above is indeed live. The good folks at
Re/code do pay me, but there’s nothing like a little monetary tip from
loyal readers to boost your self esteem on a Monday morning. Plus — and
this may be TMI — I really could use a new suit for the Code conference
since the only one I own has recently become a little snug in all the wrong
places.)
The idea is that small-business service providers such as contractors,
wedding photographers or musical instructors could have customers pay
quickly at their Cash.me page instead of relying on cash or check payments.
Square believes nonprofits will be attracted to the service’s simplicity,
too, marketing the link to followers on social media networks such as
Twitter and Facebook for fundraising purposes. Wikipedia and Red, the
nonprofit working to fight AIDS, have launched Cash.me pages to accept
donations.
Square is charging businesses and nonprofits 1.5 percent per transaction for
Square Cash payments, well below the typical 2.75 percent that Square
charges businesses to process credit card and debit card transactions
through its traditional payment service. Square is able to offer the lower
fee because debit card payments are typically cheaper to process than credit
card payments. Square hopes the fee will be low enough to convince lots of
business owners who typically only accepted cash or checks because credit
card fees were too high, to start accepting some card payments. (Square is
trusting that businesses and nonprofits will sign up for a Cash Pro account,
which includes the processing fee, rather than going around the system and
conducting business through a regular consumer account, which is free. A
spokesperson said the company is confident that it can identify when someone
is using a regular account regularly for commercial purposes.)
The move helps explain why Square launched what was initially a free
consumer product in Square Cash in the first place. Square now has a built-
in base of Square Cash users with linked debit card accounts for business
owners and nonprofits to market to. Square Cash also now has some
differentiation from its competitors since businesses can get paid through
Cash without downloading an app (though customers and donors can also search
for, and pay, businesses and nonprofits through the app).
Venmo, a Square Cash competitor owned by PayPal, has become wildly popular
on college campuses and among 20-something professionals; but anyone who
wants to pay someone through Venmo has to download the app. Venmo is much
larger than Square Cash, however. Its payment volume came in a tad above $
900 million in the fourth quarter, or $3.6 billion on an annualized basis.
Square said on Monday that Square Cash’s annualized volume run rate is $1
billion. Facebook, too, will soon introduce its own payments service,
through the Facebook Messenger app. The company hasn’t said when or if
entrepreneurs, business owners or nonprofits will be able to accept payments
through the service.

r*h2015-04-16 07:04

3 楼

第一题同不懂。。

free

【在 w********g 的大作中提到】

: 都是C++的题：
: 怎么找memory leak
: 我回答有现成的工具但我没用过。也可以自己写个计数器记录new/delete/malloc/free
: 的次数，在runtime边运行边记录。他追问：整个project就一个计数器吗？我回答每个
: class一个计数器。不知对错。
: TCP和UDP的区别
: STL里map和hashmap的区别
: 什么是纯虚函数
: 如果父类有一个纯虚函数，子类却没有覆盖这个纯虚函数，那么子类对象调用这个函数
: 时会怎样？

n*e2015-04-16 07:04

4 楼

有了一個多月了，VISA / MasterCard debit card only，prepaid 和 VGC 都不行。沒
什麼搞頭。
倒是 Square Cash personal 版本免費，用來朋友間轉賬，或者自己多個銀行間轉賬還
不錯，及時到帳，比 Paypal 簡單快速。
而且現在 refer 註冊，能拿 $5

r*e2015-04-16 07:04

5 楼

查memory leak最简单的是reference counting
应该是每个allocated object一个计数器

free

【在 w********g 的大作中提到】

m*22015-04-16 07:04

6 楼

really? 已经有八个square cash account了，怎么没想到这个promotion呢！是这个
promotion吗？
Receive a $5 bonus when a friend sends you a referral link to Square cash
and you link a debit card.
If you refer a friend and they link a debit card, then you’ll also a $5
bonus
If you’re already using the app or have used it in the past, you don’t
qualify for this offer
Must live in the United States
You must refer your friend by using their phone number

【在 n******e 的大作中提到】

: 有了一個多月了，VISA / MasterCard debit card only，prepaid 和 VGC 都不行。沒
: 什麼搞頭。
: 倒是 Square Cash personal 版本免費，用來朋友間轉賬，或者自己多個銀行間轉賬還
: 不錯，及時到帳，比 Paypal 簡單快速。
: 而且現在 refer 註冊，能拿 $5

r*e2015-04-16 07:04

7 楼

纯虚函数
如果是C++，子类要实例化的话必须实现父类的pure virtual function
否则编译都过不了啊，会在创建子类实例的时候报错
就算能过编译的话，子类的vtable的那个函数entry是null，估计调用会crash

free

【在 w********g 的大作中提到】

e*u2015-04-16 07:04

8 楼

这是避免memory leak吧，所谓的smart pointer

【在 r*******e 的大作中提到】

: 查memory leak最简单的是reference counting
: 应该是每个allocated object一个计数器
:
: free

r*e2015-04-16 07:04

9 楼

避免的意思不就是检测到可能的leak然后自动回收吗？
检测的思路是一样的

【在 e******u 的大作中提到】

: 这是避免memory leak吧，所谓的smart pointer

e*u2015-04-16 07:04

10 楼

哦，也可以这么理解
不过貌似有那种测runtime内存泄漏的工具的吧

【在 r*******e 的大作中提到】

: 避免的意思不就是检测到可能的leak然后自动回收吗？
: 检测的思路是一样的

r*e2015-04-16 07:04

11 楼

工具有很多，最常见的免费的valgrind和收费的IBM purify
不过面试应该不是问用什么工具，而是用什么思路
ref counting是一种，另一种是mark & sweep
在任意时候遍历所有的stack和global vars，看他们能reach到哪些objects，作上标记
然后遍历整个memory set，没标记而又显示in use的就是leak

【在 e******u 的大作中提到】

: 哦，也可以这么理解
: 不过貌似有那种测runtime内存泄漏的工具的吧