C++ code summary
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.
#include<iostream>
#include<fstream>
#include<map>
#include<string>
#include<algorithm> using namespace std; string &trans(string &s)
{
for (int p=; p<s.size(); p++){
if (s[p] >= 'A' && s[p] <= 'Z')
s[p] -= ('A'-'a');
else if (s[p] == ',' || s[p] == '.')
s.erase(p,);
} return s;
} int main(int argc, char *argv[])
{
ifstream in(argv[]);
if (!in){
cout<<"failed to open file !"<<endl;
exit();
} map<string, size_t> word_count;
string word;
while(in>>word)
++word_count(trans(word)); for (const auto &w:word_count)
cout<< w.first << " occurs " << w.second << " times " <<endl; return ;
}
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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");
}
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");
}