本博文主要讲解了count count_if 的使用
实例 #include <iostream> #include <algorithm> using namespace std; int main() { int a[] = {1,2,3,4,5,6,6,7,8,9}; int len = sizeof(a)/sizeof(int); cout<<"请输入你想查询的数："<<endl; int wantNum; cin>>wantNum; int nCount = count(a,a+len,wantNum); cout<<wantNum<<"出现的次数为："<<nCount<<endl; system("pause"); return 0; }2.实例2
/* *【1】查询有多少学生成绩为80 *【2】查询有多少学生成绩大于80 *【3】查询有多少学生成绩小于80 */ #include <iostream> #include <algorithm> #include <vector> #include <functional> using namespace std; class student { public: int stdno; string strName; int grade; student(int stdno,string strName,int grade) { this->stdno = stdno; this->strName = strName; this->grade = grade; } bool operator==(int grade) { return this->grade == grade; } }; // class macthExpress { int grade; public: macthExpress(int grade) { this->grade = grade; } bool operator() (student s) { return s.grade > grade; } }; class macthExpressLow { int grade; public: macthExpressLow(int grade) { this->grade = grade; } bool operator() (student s) { return s.grade < grade; } }; int main() { vector<student>stdVec; student s1(1,"lijia",100); student s2(2,"renyin",60); student s3(3,"zhangchen",90); student s4(4,"xiaodeguang",80); student s5(5,"weiyimeng",80); stdVec.push_back(s1); stdVec.push_back(s2); stdVec.push_back(s3); stdVec.push_back(s4); stdVec.push_back(s5); ///等于80分的个数 int nCount = count(stdVec.begin(),stdVec.end(),80); cout<<"分数等于80分的有"<<nCount<<"个"<<endl; //大于80分的个数 nCount = count_if(stdVec.begin(),stdVec.end(),macthExpress(80)); cout<<"大于80分的个数："<<nCount<<endl; //小于80分的个数 nCount = count_if(stdVec.begin(),stdVec.end(),macthExpressLow(80)); cout<<"小于80分的个数："<<nCount<<endl; system("pause"); return 0; }