《CPlusPlusPrimer》第十二章二节编程源码——vocab功能的源码

// 练习C++Primer Chapter12.2节中的泛型算法

#include <iostream>
#include <fstream>
#include <algorithm>
#include <vector>
#include <string>

using namespace std;

typedef vector<string> textwords;
typedef vector<string>::iterator VEC_STR_IT;

class PrintElem{
int line_len;
int cnt;
public:
PrintElem(int len = 8): line_len(len), cnt(0) {}
void operator()(const string & elem)
{
cnt++;
cout << elem << " ";
if( cnt % line_len == 0)
{
cout << '\n';
}
}
};

class LessThan
{
public:
bool operator()(const string &str1, const string &str2)
{
// OK，必须用size，而非length.
return (str1.size() < str2.size());
}
};

class GreatThan
{
int _len;
public:
GreatThan(int len = 6) : _len(len) {}
bool operator() ( const string & s)
{
return (s.size() > _len);
}
};

void proccess_vocab(const vector<textwords> &vecs)
{
vector<string> texts;
vector<textwords>::const_iterator iter = vecs.begin();
for( ; iter != vecs.end(); iter++ )
{
copy( (*iter).begin(), (*iter).end(), back_inserter( texts ));
}
sort( texts.begin(), texts.end() );
for_each( texts.begin(), texts.end(), PrintElem());
cout << "\n\n";

// 消除相同词
VEC_STR_IT it;
it = unique( texts.begin(), texts.end());
texts.erase(it, texts.end());
for_each( texts.begin(), texts.end(), PrintElem());
cout << "\n\n";

// 根据自符串长度排序
stable_sort( texts.begin(), texts.end(), LessThan());
for_each( texts.begin(), texts.end(), PrintElem());
cout << "\n\n";

// 计算长度大于6的个数
int cnt  = count_if( texts.begin(), texts.end(), GreatThan());
cout << "the count which's size is great than 6 is: " << cnt << endl;

static string rw[] = {"and", "if", "or", "but", "the"};
vector<string> remove_words ( rw, rw + 5);
VEC_STR_IT it2 = remove_words.begin();
for( ; it2 != remove_words.end(); it2++ )
{
int cnt = count ( texts.begin(), texts.end(), *it2);
cout << cnt << " instances removed: " << (*it2) << endl;

texts.erase(
remove(texts.begin(), texts.end(), (*it2)),
texts.end());
}
cout << "\n\n";

for_each( texts.begin(), texts.end(), PrintElem());
}

int main( char* args[], int argc)
{
vector<textwords> sample;
vector<string> vec1, vec2;
const string inf1 = "chapter12_vocab_file1.txt", inf2 = "chapter12_vocab_file1.txt";

using std::ifstream;
ifstream infile1(inf1.c_str());
ifstream infile2(inf2.c_str());

istream_iterator<string> input_set1(infile1), eos;
istream_iterator<string> input_set2(infile2);

copy( input_set1, eos, back_inserter(vec1));
copy(input_set2, eos, back_inserter(vec2));

sample.push_back( vec1 );
sample.push_back( vec2 );

proccess_vocab(sample);

return 0;
}