Merge pull request #92 from pezy/master

Finished Chapter 9.
Merge pull request #1 from Mooophy/master

更新fork分支
Update ex6_21.cpp

使用conditional operator更简洁。
Merge pull request #93 from hcqs33/master

Update ex6_21.cpp with ternary operator.
Update README.md

Exercise 6.23的url写错了。
Merge pull request #94 from hcqs33/master

Update README.md : fix url bug for 6.23
Update README.md
Merge remote-tracking branch 'Mooophy/master'
added 10.6 to 10.10

1. added 10.7 and 10.8
2. splited 10.6 from ex10_6_9_10.cpp
3. splited 10.10 from ex10_6_9_10.cpp
4. added clang different result noting in comments.