a solution for exercise 15.42 (c)
Merge pull request #18 from Queequeg92/master

a solution for exercise 15.42 (c)
Thx for contribution.
Merge pull request #19 from pezy/master

Finished Chapter 4
Thx for contribution.
Merge pull request #20 from pezy/master

Add the links of other chapter.
update 9_45, using iterator

the problem ask we use iterator, insert and append
and i update the interface, return string is not good
ex10_25.cpp

added solution 10.25
rename and clear

added solution to 10.25
Merge pull request #22 from Surendra154/master

solution to 10.25
Merge pull request #21 from TungWah/master

update 9_45, using iterator
thx for contribution.
refactor : return string by value
	modified:   ex9_45.cpp
Update ex10_6_9_10.cpp

resize v before set0.
Merge pull request #23 from zzzkl/patch-1

Update ex10_6_9_10.cpp
remove redundant if checking
Use range for instead of for
Merge pull request #24 from pezy/master

Finished Chapter 5. Thx @pezy
Merge pull request #2 from Mooophy/master

Update with Mooophy