C++泛型算法迭代器，find,count，accumulate,fill,equal

一、find,count，查找和计数

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#include <algorithm> using namespace std; int main(int argc, char**argv) {     //泛型算法find 函数,元素查找      //vector      vector<int> vec{23,456,654,7,65,89,65,89,65,98};      auto res = find(vec.begin(),vec.end(),65);      if(res==vec.end()) //尾后迭代器用来判断是否找到元素      {          cout<<"没有找到元素"<<endl;      }      else      {          cout<<*res<<endl;      }      //数组      int ia[]={23,567,75,64,242,57,32,45};      int *result=find(begin(ia),end(ia),32);//数组指针      cout<<*result<<endl;      //数组      auto ress = find(ia+0,ia+5,75);      cout<<*ress<<endl;      //find over      //count函数统计序列中给定值的出现次数,vector list      auto cou = count(vec.begin(),vec.end(),65);      cout<<cou<<endl;      list<string> str{"sd","xf","df","vf","df","kf","gf","ef","df","cf","df","af"};      auto coup = count(str.begin(),str.end(),"df");      cout<<coup<<endl;      return 0; }

　二、accumulate 求和相加，equal对比序列，fill 容器元素重置，重新赋值

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#include <numeric> using namespace std; int main(int argc, char**argv) {     //accumulate 求和函数,0是作为求和基数      vector<int> vec{23,456,654,7,65,89,65,89,65,98};      int sum = accumulate(vec.cbegin(),vec.cend(),0);      cout<<sum<<endl;      vector<string> vecs{"da","fr","ws","vd","bg"};//对于字符串相加     // string sums = accumulate(vecs.cbegin(),vecs.cend()," ");//错误写法      string sums = accumulate(vecs.cbegin(),vecs.cend(),string("sums = "));      cout<<sums<<endl;      //equal序列对比函数,比较元素是否一致       vector<int> vec1{23,456,654,7,65,89,65,89,65,98,98};       bool res = equal(vec.cbegin(),vec.cend(),vec1.cbegin());       cout<<res<<endl;       //fill 容器快速赋值       vector<int> vec2{22,44,556,656};       //fill(vec2.begin(),vec2.end(),10);//全部重置       fill(vec2.begin(),vec2.begin() + 2,10);//部分重置<br><br>　　　 fill_n(vec2.begin(),2,20);//部分修改       for(auto iter = vec2.begin();iter!=vec2.end();iter++)       {           cout<<*iter<<endl;       }      return 0; }

　三、 copy拷贝，replace ,replace_copy替换函数

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using namespace std; int main(int argc, char**argv) {      //copy 算法      int a1[]={0,1,2,3,4,5};      int a2[sizeof(a1)/ sizeof(*a1)];//大小一致      auto ret = copy(begin(a1),end(a1),a2);//拷贝a1给a2,ret指向a2尾后元素      //cout<<*(ret-1)<<endl;      for(auto iter = begin(a2);iter!=end(a2);iter++)      {         // cout<<*iter<<endl;      }             //replace 元素替换函数      list<int> vec{2,4,6,8,9,0,3};      replace(vec.begin(),vec.end(),0,20);//找0替换成20      //拷贝替换,不改变原vector      list<int> vec2;      replace_copy(vec.cbegin(),vec.cend(),back_inserter(vec2),0,20);// 拷贝并替换      for(auto iter = vec2.begin();iter!=vec2.end();iter++)      {          cout<<*iter<<endl;      }      return 0; }