1.判断两个日期间的天数

class test {
public:int y, m, d, x;test(){y = 2023, m = 3, d = 1, x = 3;}test(int yy, int mm, int dd){y = yy;m = mm;d = dd;}void ReturnWeekDay(){int iWeek = 0;int Y = 0, C = 0, M = 0, D = 0;if (m == 1 || m == 2){C = (y - 1) / 100;Y = (y - 1) % 100;M = m + 12;D = d;}else{C = y / 100;Y = y % 100;M = m;D = d;}iWeek = Y + Y / 4 + C / 4 - 2 * C + 26 * (M + 1) / 10 + D - 1;iWeek = iWeek >= 0 ? (iWeek % 7) : (iWeek % 7 + 7);if (iWeek == 7){iWeek = 0;}cout << "today is weekday:" << iWeek << endl;}
};
int main()
{test t(2013,3,3);t.ReturnWeekDay();return 0;
}

2.对学生成绩排序

struct S
{int grade;int number;int score;bool operator == (S s){return score == s.score;}
};
class test
{
private:list<S>a;list<S>::iterator p;int n, i;static int m;
public:test(int nn){S temp;n = nn;srand(time(0));for (i = 0; i < n; ++i){temp.grade = rand() % 4 + 1;temp.number = rand();temp.score = rand()%99;a.push_back(temp);}}void browse(){for (p = a.begin(); p != a.end(); ++p){cout << p->grade << "-" << p->number << "-" << p->score << endl;}}static bool sort1(S s1, S s2){return s1.score < s2.score;}void Sort(){a.sort(sort1);}static bool find1(S s){return s.score >= 80;}static bool find2(S s){return s.grade == m;}void turn(){int num = 0;p = a.begin();while (1){p = find_if(p, a.end(), find1);if (p != a.end()){++num;++p;}else break;}cout << num << endl;cout << "input delete:" << endl;cin >> m;p = a.begin();while (1){p = find_if(p, a.end(), find2);if (p != a.end()){p = a.erase(p);++p;}else break;}for(;p != a.end();++p){if (p->grade == m){a.erase(p);}else break;}}
};
int test::m;
int main()
{test t(10);t.Sort();t.browse();cout << "==========" << endl;t.turn();t.browse();return 0;
}

3.简单排序

class test
{
protected:int n;
public:test(){n = 10;}test(int nn ){n = nn;}static bool sort1(int n1, int n2)						//必须静态{return n1 > n2;						//实现从大到小排序}void output() {int x = 0;int i = 0;int* p = new int[n];for (i = 0; i < n; i++){x = rand() % 89 + 11;p[i] = x;}sort(p,p + n,sort1);for (i = 0; i < 3; i++){cout << p[i] << endl;}}
};
class test1:public test
{
protected:int m;
public:test1(){m = 2;}test1(int nn,int mm):test(nn){m = mm;}void turn(){srand(time(0)+rand());int i = 0;for (i = 0; i < m; i++){test1* p = new test1(*this);p->output();delete p;}}
};
int main()
{test1 t(10,2);t.turn();return 0;
}

4.文件操作  查找指定字符

class test
{
private:string s, s1;string::size_type n, n1, n2, pos;ifstream f;
public:test(){}void turn(){f.open("dictionary.txt", ios::in);if (!f){cout << "file error!" << endl;}string temp;cout << "input word:";cin >> temp;while (!f.eof()){getline(f, s);if (temp == Word(s)){cout << s << endl;break;}}f.close();}string Word(string s){n = s.find(" ", 0);s1 = s.substr(0, n);return s1;}
};
int main()
{test t;t.turn();return 0;
}class test {
private:fstream f; string::size_type n; map<string, string>a;map<string, string>::iterator p;
public:test(){string s, s1;f.open("dictionary.txt", ios::in); while (true){getline(f, s); n = s.find(" ", 0); s1 = s.substr(0, n); a.insert(pair<string, string>(s1, s)); if (f.eof())break;}} ~test() { f.close(); }void FIND() {string word;cout << "input word:";cin >> word;p = a.find(word);if (p != a.end()){cout << p->second << endl;}else cout << "no word!" << endl;}
};
int main()
{test t;t.FIND(); return 0;
}