{

{//9.1.2 输出流迭代器 Ex9_02.cpp

std::vector<std::string> words{"The", "quick", "brown", "fox", "jumped", "over", "the", "lazy", "dog"};

{

std::ostream_iterator<std::string> out_iter{std::cout};

for(const auto& word : words) {

*out_iter++ = word;

*out_iter++ = " ";

}

*out_iter++="\n";

}

{

std::ostream_iterator<std::string> out_iter{std::cout};

for(const auto& word : words) {

(out_iter=word)=" ";

}

out_iter="\n";

}

{

std::ostream_iterator<std::string> out_iter{std::cout, " "};

std::copy(std::begin(words), std::end(words), out_iter);

out_iter="\n";

}

{

std::copy(std::begin(words), std::end(words), std::ostream_iterator<std::string>{std::cout, " "});

std::cout << std::endl;

}

}

//9.4 流迭代器和算法(部分源码)

//

//从文件读入。

//string file_in{"filename.txt"};

//std::ifstream in(file_in);

//std::istream_iterator<string>{in}

//

//向文件写出。

//string file_out{"filename.txt"};

//std::ofstream out(file_out);

//std::ostream_iterator<string>{out}

{// Ex9_07.cpp

string file_name{"data/fibonacci.txt"};

std::fstream fibonacci{file_name,

std::ios_base::in | std::ios_base::out | std::ios_base::trunc};

if(!fibonacci){

std::cerr<<file_name<<" not open." <<std::endl;

exit(1);

}

unsigned long long first{}, second{1};

auto iter = std::ostream_iterator<unsigned long long>{fibonacci, " "};

(iter=first)=second;//向iter写入两个数据，iter赋值运算符返回一个iter

const size_t n{50};

std::generate_n(iter,

n,

[&first, &second](){

auto result=first+second;

first=second;

second=result;

return result; });

fibonacci.seekg(0);

std::for_each(std::istream_iterator<unsigned long long>{fibonacci},

std::istream_iterator<unsigned long long>{},

[](unsigned long long k){

const size_t perline{6};

static size_t count{};

std::cout << std::setw(12)<<k<<((++count%perline)?" ":"\n");});

std::cout<<std::endl;

fibonacci.close();

}

{// Ex9_08.cpp

string file_name{"data/temperatures.txt"};

{

std::ofstream temps_out{file_name, std::ios_base::out |std::ios_base::trunc};

const size_t n{50};

std::random_device rd;

std::mt19937 rng{rd()};

double mu{50.0}, sigma{15.0};

std::normal_distribution<> normal{mu, sigma};

std::generate_n(std::ostream_iterator<double>{temps_out, " "},

n,//写出n个数据

[&rng, &normal](){return normal(rng);});

temps_out.close();

}

{

//std::ifstream temps_in{file_name, std::ios_base::in|std::ios_base::trunc};//error

std::ifstream temps_in{file_name, std::ios_base::in};//ok

//std::ifstream temps_in{file_name};//ok

std::for_each(std::istream_iterator<double>{temps_in},

std::istream_iterator<double>{},

[](double t) {//读入double数据, 打印

const size_t perline{10};

static size_t count{};

std::cout<<std::fixed<<std::setprecision(2)<<std::setw(5)

<<t<<((++count%perline)?" ":"\n");});

std::cout<<std::endl;

temps_in.close();

}

}

{//9.5 流缓冲区迭代器 std::istreambuf_iterator/std::ostreambuf_iterator

{//9.5.2 输出缓冲流迭代器

string ad{"Now is the discount of our winter tents!\n"};

{

std::ostreambuf_iterator<char> iter{std::cout};

for(auto c:ad){

iter = c;

}

}

{

std::copy(std::begin(ad),

std::end(ad),

std::ostreambuf_iterator<char>{std::cout});

}

{

std::cout<<ad;

}

{//对于char来讲，buf与否效果都是一样的。

std::ostream_iterator<char> iter{std::cout};

for(auto c:ad){

iter=c;

}

}

/***

}

{//9.5.3

string file_name{"data/dictionary.txt"};

std::ifstream file_in{file_name};

if(!file_in) {

std::cerr<< file_name << " not open." << std::endl;

exit(1);

}

string file_copy{"data/dictionary_copy.txt"};

std::ofstream file_out{file_copy, std::ios_base::out|std::ios_base::trunc};

std::istreambuf_iterator<char> in{file_in};

std::istreambuf_iterator<char> end_iter{};

std::ostreambuf_iterator<char> out{file_out};

while(in!=end_iter) {

//out = *in++;//OK

out++ = *in++;//OK

*out++ = *in++;//OK

//out = *in;//compile OK, logic wrong.

//out = in;//compile error!

}

std::cout<<"File copy completed."<<std::endl;

file_in.close();

file_out.close();

}

//类对象的序列化和反序列化请参考ProtoBuff

{//9.6 string流,见ch09_cin.cpp

}

}

return 0;