vector排序与查找

本示例使用比较函数，函数对象进行vector的排序与查找操作。

#include <algorithm>
#include <vector>
using namespace std;

#define MAX_NAME_LEN    32
struct Student
{
    int     no;
    char    name[MAX_NAME_LEN];
    int     age;

    bool operator==(const Student& other) const
    {
        return no == other.no;
    }

    bool operator==(int studentNo) const
    {
        return no == studentNo;
    }
};

typedef std::vector<Student> TVecStudent;

Student g_students[] = 
{
    {1,     "James",    17},
    {2,     "Tom",      16},
    {3,     "David",    18},
    {4,     "Paul",     15},
};

void InitStudent(TVecStudent& students)
{
    students.assign(&g_students[0], &g_students[0] + sizeof(g_students)/sizeof(g_students[0]));
}

void PrintStudent(const Student& student)
{
    printf("no:%d, name:%s, age:%d\n", student.no, student.name, student.age);
}

void PrintStudents(TVecStudent& students)
{
    TVecStudent::const_iterator iter = students.begin();
    for (; students.end() != iter; ++iter)
    {
        const Student& student = *iter;
        PrintStudent(student);
    }
}

// 小于比较函数运算子
bool lessStudentAge(const Student& lft, const Student& rht)
{
    return lft.age < rht.age;
}

// 大于比较函数对象运算子
struct GreaterAgeSorter
{
    bool operator()(const Student& lft, const Student& rht)
    {
        return lft.age > rht.age;
    }
};

// 学号查找函数对象运算子
struct StudentNoFinder
{
    StudentNoFinder(int no)
    {
        m_no = no;
    }
    bool operator()(const Student& student) const
    {
        return student.no == m_no;
    }

private:
    int m_no;
};

 

测试代码：

void testVector()
{
    TVecStudent students;
    InitStudent(students);

    printf("Origin students:\n");
    PrintStudents(students);

    std::sort(students.begin(), students.end(), lessStudentAge);

    printf("\n\nSorted by age asc:\n");
    PrintStudents(students);


    std::sort(students.begin(), students.end(), GreaterAgeSorter());

    printf("\n\nSorted by age desc:\n");
    PrintStudents(students);

    TVecStudent::const_iterator itFind;
    itFind = std::find(students.begin(), students.end(), 1);
    if (students.end() != itFind)
    {
        printf("\n\nStudent found:\n");
        PrintStudent(*itFind);
    }

    itFind = std::find_if(students.begin(), students.end(), StudentNoFinder(2));
    if (students.end() != itFind)
    {
        printf("\n\nStudent found:\n");
        PrintStudent(*itFind);
    }
}

int main()
{
    testVector();

    return 0;
}

 

输出结果：

Origin students:
no:1, name:James, age:17
no:2, name:Tom, age:16
no:3, name:David, age:18
no:4, name:Paul, age:15


Sorted by age asc:
no:4, name:Paul, age:15
no:2, name:Tom, age:16
no:1, name:James, age:17
no:3, name:David, age:18


Sorted by age desc:
no:3, name:David, age:18
no:1, name:James, age:17
no:2, name:Tom, age:16
no:4, name:Paul, age:15


Student found:
no:1, name:James, age:17


Student found:
no:2, name:Tom, age:16