[C++] Study Notes: 21 Days to Learn C++ Chapter 23-29 Highlights

[C++] Study Notes: 21 Days to Learn C++ Chapter 23-29 Highlights

STL algorithms are divided into two categories: non-variable order algorithms and variable order algorithms

non-variable algorithm

计数算法 count() count_if()
搜索算法 search() search_n() find() find_if() find_end() find_first_of() adjacent_find()
比较算法 equal() mismatch() lexicographical_compare()

Variation Algorithm

初始化算法 fill() fill_n() generate() fenerate_n()
修改算法for_each() transform()
复制算法 copy() copy_backward()
删除算法 remove() remove_if() remove_copy() remove_copy_if() unique() unique_copy()
替换算法 replace() replace_if()
排序算法 sort() stable_sort() partial_sort() partial_sort_copy()

Algorithms Available for Sorted Containers

binary_search() lower_bound() upper_bound()

look up

auto element = find(numsInVec.cbegin(),numsInVec.cend(),numToFind);
auto element = find_if(numsInVec.cbegin(),numsInVec.cend(),[](int element){return (element%2)==0;});
if (element != numInVec.end())
 cout << “Result:Value found!” << endl;

count

size_t numZeros = count(numsInVec.cbegin(),numsInVec.cend(),0);
size_t numZeros = count_if(numsInVec.cbegin(),numsInVec.cend(),IsEven<int>);

search string

auto range = search(numsInVec.cbegin(),numsInVec.cend((),numsInList.cbegin(),numsInList.cend());
auto partialRange = search_n(numInVec.cbegin(),numsInVec.cend(),n,value);

filling

fill(numsInVec.begin(),numsInVec.end(),value);
fill_n(numsInVec.begin(),n,value);

generate

generate(numsInVec.begin().numsInVec.end(),rand);
generate_n(numdInList.begin(),n,rand);

Process one by one

for_each(start_of_range,end_of_range,unaryFunctionObject);

convert

transform(str.cbegin(),str.cend(),strLowerCaseCopy.begin(),::tolower);
transform(numsInVec.cbegin(),numsInVec.cend(),numsInVec2.cbegin(),sumInDeque.begin(),plus<int>());

copy

auto lastElement = copy(numsInList.cbegin().numsInList.cend(),numsInVec.begin());
copy_if (numsInList.cbegin().numsInList.cend(), lastElement,[](int elemet){return ((element%2)==1);});
copy_backward(numsInList.cbegin().numsInList.cend(),numsInVec.begin());

remove

auto newEnd = remove(numsInVec.begin(),numsInVec.end(),0);
//auto newEnd = remove_if(numsInVec.begin(),numsInVec.end(),[](int num){return ((num%2)==1);});
numsInVec.erase(newEnd,nemsInVec.end());

replace

replace(numsInVec.begin(),numsInVec.end(),value_to_be_replaced,value);
replace(numsInVec.begin(),numsInVec.end(),[](int element){return ((element%2)==0);},value);

to sort

sort(numsInVec.begin(),numsInVec.end()); // ascending order
sort(numsInVec.begin(),numsInVec.end(),[](int lhs,int rhs){return (lhs>rhs);}); // descending order

Deduplication

auto newEnd = unique(numsInVec.begin(),numsInVec.end());
numsInVec.erase(newEnd,numsInVec.end());

binary search

bool elementFound = binary_search(numsInVec.begin),numsInVec.end(),value);
if(elementFound)
	cout << “Element found in the vector!” << endl;

stable_sort() will ensure that the relative order of the sorted elements remains the same

range partition

partion(numsInVec.begin(),numsInVec.end(),IsEven);
stable_partion(numsInVec.begin(),numsInVec.end(),IsEven);

inserts elements into a sorted set

auto minInsertPos = lower_bound(names.begin(),names.end(),str);
auto maxInsertPos = upper_bound(names.begin(),names.end(),str);

Use remove() remove_if() unique() Be sure to use erase() to resize the container

stack 成员函数push() pop() empty() size() top()
queue成员函数 push() pop() front() back() empty() size()
priority_queue成员函数 push() pop() top() empty() size()

Member method of bitset set() set(N,val=1) reset() reset(N) flip() size() count()

Smart pointer unique_pointer whose copy constructor and assignment operator are declared private

When writing applications that use multiple threads, consider using std::shared_ptr and std::weak_ptr

exception handling

try
{
	// code made exception safe
}
catch(...) // catch(const std::exception& exp)
{
	cout << “Exception in SomeFunc(), quitting” << endl;
}

custom exception class

class CustomException: public std::exception
{
	string reason;
public:
	// constructor, needs reason
	CustomException(const char* why):reason(why){}

	// redefining virtual function to return ‘reason’
	virtual const char* what() const throw()
	{
	return reason.c_str();
	}
}

Most operating systems provide semaphores and mutexes to synchronize threads.