C++ code summary
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map<int, PersonClassifier>::iterator it与 map<int, PersonClassifier> it的区别与联系
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C++ 并行程序的执行:
int coreNum = omp_get_num_procs();
#pragma omp parallel for num_threads(coreNum) default(none) \
private(po_num, it, queryLabel) \
shared(al_random_select_num, satisfy_size, satisfy_classifier_label, not_selected, random_index)
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对输入的句子,统计每一个单词出现的次数:
int main() {
map<string, size_t> word_count;
string word;
while (cin >> word) {
++word_count[word];
}
for (constauto &w : word_count)
cout << w.first <<"occurs"<< w.second
<< ((w.second > 1) ? "times" : "time") << endl;
system("pause");
}
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统计输入中每一个单词出现的次数(排除常见单词,如:”the”, ”a”, ”an”等等)
#include<iostream>
#include<string>
#include<map>
#include<set>
usingnamespace std;
int main() {
map<string, size_t> word_count;
set<string> exclude = {"the", "a", "an"};
string word;
while (cin >> word)
if (exclude.find(word) == exclude.end())
++word_count[word];
for (constauto &w : word_count)
cout << w.first <<" occurs "<< w.second <<" times "<< endl;
system("pause");
}
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忽略大小写和标点,如:”example,” “example.” “Example”应该递增相同计数器。
分为3步骤:
1.先将所有的大写字母改为小写;
2.将所有的标点符号都删去;
3.将转换好的字符串返回.
1 #include<iostream> 2 #include<fstream> 3 #include<map> 4 #include<string> 5 #include<algorithm> 6 7 using namespace std; 8 9 string &trans(string &s) 10 { 11 for (int p=0; p<s.size(); p++){ 12 if (s[p] >= 'A' && s[p] <= 'Z') 13 s[p] -= ('A'-'a'); 14 else if (s[p] == ',' || s[p] == '.') 15 s.erase(p,1); 16 } 17 18 return s; 19 } 20 21 int main(int argc, char *argv[]) 22 { 23 ifstream in(argv[1]); 24 if (!in){ 25 cout<<"failed to open file !"<<endl; 26 exit(1); 27 } 28 29 map<string, size_t> word_count; 30 string word; 31 while(in>>word) 32 ++word_count(trans(word)); 33 34 for (const auto &w:word_count) 35 cout<< w.first << " occurs " << w.second << " times " <<endl; 36 37 return 0; 38 }
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对关联容器进行值初始化:
map<string, size_t> word_count;
set<string> exclude = {“the”, ”but”, “and”};
map<string, string> authers = { {“wang”, “xiao”}, {“wang”, ”kui”}, {“wang”, ”jianjun”} };
#include<iostream>
#include<string>
#include<map>
#include<set>
#include<vector>
usingnamespace std;
int main() {
vector<int> ivec;
for (vector<int>::size_type i = 0; i != 20; ++i) {
ivec.push_back(i);
ivec.push_back(i);
}
set<int> iset(ivec.cbegin(), ivec.end());
multiset<int> miset(ivec.cbegin(), ivec.cend());
cout << ivec.size() << endl;
cout << iset.size() << endl;
cout << miset.size() << endl;
system("pause");
}
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pair类型:
一个pair保存两个数据成员,pair是一个用来生成特定类型的模板。
pair<string, string> anon;
pair<string, size_t> word_count;
pair<string, vector<int>> line;
pair<string, string> auther {“wangxiao”, “wangkui”};
pair类型的数据成员是public的,两个成员分别为 first 和 second。
9. ----
#include<iostream>
#include<string>
#include<map>
using namespace std;
int main() {
map<string, size_t> word_count;
string word;
while (cin >> word) {
++word_count[word];
}
for (const auto &w : word_count)
cout << w.first << "occurs" << w.second
<< ((w.second > 1) ? "times" : "time") << endl;
system("pause");
}