文章目錄

• • • 3.4 迭代器介紹
    • • 3.4.1 使用迭代器
      • 3.4.2 迭代器運算

3.4 迭代器介紹

3.4.1 使用迭代器

3.21

#include<vector> #include<iostream> #include<string> using namespace std;int main(){vector<int> v1;vector<int> v2(10);vector<int> v3(10,42);vector<int> v4{10};vector<int> v5{10,42};vector<vector<int>> v{v1,v2,v3,v4,v5};vector<string> v6{10};vector<string> v7{10 , "hi"};vector<vector<string>> vv{v6,v7};for(auto it = v.cbegin(); it != v.cend(); ++it){for(auto it2 = (*it).cbegin(); it2 != (*it).cend(); ++it2){cout<<*it2<<" ";}cout<<endl;/*為什么用(*it)： As the error states, you are calling begin() on a std::vector<double>::iterator.You should call that on a std::vector<double>, so that it could return you a std::vector<double>::iterator.*/} for(auto it = vv.cbegin(); it != vv.cend(); ++it){for(auto it2 = (*it).cbegin(); it2 != (*it).cend(); ++it2){cout<<*it2<<" ";} cout<<endl;}return 0; } /*0 0 0 0 0 0 0 0 0 0 42 42 42 42 42 42 42 42 42 42 10 10 42hi hi hi hi hi hi hi hi hi hi */

3.22

#include<vector> #include<iostream> #include<string> using namespace std;int main(){vector<string> test;string line;while(getline(cin,line)){test.push_back(line);}for(auto it = test.begin(); it != test.end() && !it->empty(); ++it){//輸出test每一行，直到遇到空白行為止。 for(auto it2 = it->begin(); it2 != it->end(); ++it2)*it2 = toupper(*it2);cout<<*it<<endl; }return 0; } /* ksjfsjfjls sdfjsjfl sdoifjdsoijgofjdgspgojospdjsp.ds jodijo jo ojo ssd sdjfod ^Z KSJFSJFJLS SDFJSJFL SDOIFJDSOIJGOFJDGSPGOJOSPDJSP.DS JODIJO JO OJO SSD SD */

3.23

#include<vector> #include<iostream> #include<string> using namespace std;int main(){vector<int> a(10,2);for(auto i = a.begin(); i != a.end(); ++i){*i = (*i)*2;cout<<*i<<' ';} } //4 4 4 4 4 4 4 4 4 4

3.4.2 迭代器運算

3.24

#include<vector> #include<iostream> #include<string> using namespace std;int main(){vector<int> a;int b;while(cin>>b){a.push_back(b);}auto beg = a.begin();auto end = a.end()-1;while(beg<=end){if(beg==end) cout<<*beg;elsecout<<*beg + *end;beg++;end--;cout<<' ';}return 0; } /* 1 2 3 4 ^Z 5 5 */ /* 1 2 3 4 5 ^Z 6 6 3 */

3.25

#include<vector> #include<iostream> #include<string> using namespace std;int main(){vector<unsigned> scores(11,0);unsigned grade;auto i = scores.begin();while(cin>>grade){if(grade <= 100)*(i + grade/10)+=1;}for(auto i = scores.begin(); i != scores.end(); ++i){cout<<*i<<" ";}return 0; } /* 42 65 95 100 39 67 95 76 88 76 83 92 76 93 ^Z 0 0 0 1 1 0 2 3 2 4 1 */

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