程序设计实习实验班2017作业(C++ 作业2, 3, 6, 7)
01:编程填空：学生信息处理程序
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#include <iostream> #include <string> #include <cstdio> #include <cstring> #include <sstream> #include <cstdlib> using namespace std; class Student { private: string name; int age, id; int score[5]; double ave; public: Student(){ name = ""; memset(score, 0, sizeof(score)); age = id = ave = 0; } void input(){ string str; int tmp = 0, num = 0; getline(cin, str); str += ','; for(int i = 0; i < str.length(); i++) if(str[i] == ',') { if(num == 1)age = tmp; if(num == 2)id = tmp; if(num > 2)score[num - 2] = tmp; tmp = 0; num++; } else { if(num == 0)name += str[i]; else tmp = tmp * 10 + str[i] - '0'; } } void calculate(){ for(int i = 1; i <= 4; i++) ave += score[i]; ave /= 4; } void output(){ cout << name << ',' << age << ',' << id << ',' << ave << endl; } }; int main() { Student student; // 定义类的对象 student.input(); // 输入数据 student.calculate(); // 计算平均成绩 student.output(); // 输出数据 } |
02:返回什么才好呢
this指针
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#include <iostream> using namespace std; class A { public: int val; A(int x = 123){ val = x; } A& GetObj(){ return *this; } }; int main() { int m,n; A a; cout << a.val << endl; while(cin >> m >> n) { a.GetObj() = m; cout << a.val << endl; a.GetObj() = A(n); cout << a.val<< endl; } return 0; } |
03:第三周程序填空题2
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#include <iostream> using namespace std; class A { public: int val; A(){ val = 0; } int& GetObj(){ return val; } }; main() { A a; cout << a.val << endl; a.GetObj() = 5; cout << a.val << endl; } |
05:第四周程序填空题1
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#include <iostream> #include <cstring> #include <cstdlib> using namespace std; class Complex { private: double r,i; public: void Print() { cout << r << "+" << i << "i" << endl; } Complex& operator=(const string& x){ bool opt = 0; this->r = this->i = 0; for(int i = 0; i < x.length(); i++) if(x[i] == '+')opt = 1; else if(x[i] >= '0' && x[i] <= '9') { if(opt)this->i = this->i * 10 + x[i] - '0'; else this->r = this->r * 10 + x[i] - '0'; } return *this; } }; int main() { Complex a; a = "3+4i"; a.Print(); a = "5+6i"; a.Print(); return 0; } |
06:第四周程序填空题3
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#include <iostream> #include <cstring> using namespace std; class Array2 { private: int *a; int i,j; public: Array2(){a = NULL;} Array2(int _i, int _j){ i = _i, j = _j; a = new int[i * j]; } Array2(Array2 &t){ i = t.i; j = t.j; a = new int[i * j]; memcpy(a, t.a, sizeof(int) * i * j); } int* operator[](int _i){ return a + _i * j; } int operator()(int _i, int _j){ return a[_i * j + _j]; } }; int main() { Array2 a(3,4); int i,j; for( i = 0;i < 3; ++i ) for( j = 0; j < 4; j ++ ) a[i][j] = i * 4 + j; for( i = 0;i < 3; ++i ) { for( j = 0; j < 4; j ++ ) { cout << a(i,j) << ","; } cout << endl; } cout << "next" << endl; Array2 b; b = a; for( i = 0;i < 3; ++i ) { for( j = 0; j < 4; j ++ ) { cout << b[i][j] << ","; } cout << endl; } return 0; } |
07:第三周程序填空题4
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#include <iostream> using namespace std; class Base { public: int k; Base(int n):k(n) { } }; class Big { public: int v; Base b; public: Big():b(0){} Big(int x):v(x),b(x){} }; int main() { Big a1(5); Big a2 = a1; cout << a1.v << "," << a1.b.k << endl; cout << a2.v << "," << a2.b.k << endl; return 0; } |
08:别叫，这个大整数已经很简化了!
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#include <iostream> #include <cstring> #include <cstdlib> #include <cstdio> using namespace std; const int MAX = 110; class CHugeInt { private: int *a, l; public: CHugeInt(){ a = new int[MAX]; l = 1; memset(a, 0, sizeof(int) * MAX); } CHugeInt(const CHugeInt& x){ a = new int[MAX]; memset(a, 0, sizeof(int) * MAX); l = x.l; for(int i = 1; i <= l; i++) a[i] = x.a[i]; } ~CHugeInt(){ if(a)delete [] a; } CHugeInt(int n){ a = new int[MAX]; memset(a, 0, sizeof(int) * MAX); if(!n)l = 1; else l = 0; while(n){ a[++l] = n % 10; n /= 10; } } CHugeInt(char *c){ a = new int[MAX]; memset(a, 0, sizeof(int) * MAX); l = strlen(c); for(int i = l - 1; i >= 0; i--) a[l - i] = c[i] - '0'; } int& operator[](int x){ return a[x]; } CHugeInt& operator =(const CHugeInt& x){ a = new int[MAX]; memset(a,0,sizeof(*a)); l = x.l; for(int i = 1; i <= l; i++) a[i] = x.a[i]; return *this; } friend CHugeInt operator +(CHugeInt a, CHugeInt b){ CHugeInt c; c.l = max(a.l, b.l); for(int i = 1; i <= c.l; i++) c[i] = a[i] + b[i]; for(int i = 1; i <= c.l; i++) if(c[i] >= 10) { if(i == c.l)c.l++; c[i + 1] += c[i] / 10; c[i] %= 10; } return c; } friend ostream& operator << (ostream& os, CHugeInt x){ for(int i = x.l; i >= 1; i--) os << x.a[i]; return os; } friend CHugeInt operator +(CHugeInt a, int b){ return a + CHugeInt(b); } friend CHugeInt operator +(int a, CHugeInt b){ return CHugeInt(a) + b; } CHugeInt operator +=(int x){ *this = *this + CHugeInt(x); return *this; } CHugeInt operator ++(){ *this = *this + CHugeInt(1); return *this; } CHugeInt operator ++(int){ CHugeInt tmp = *this; *this = CHugeInt(1) + *this; return tmp; } }; int main() { char s[210]; int n; while (cin >> s >> n) { CHugeInt a(s); CHugeInt b(n); cout << a + b << endl; cout << n + a << endl; cout << a + n << endl; b += n; cout << ++ b << endl; cout << b++ << endl; cout << b << endl; } return 0; } |
02:自己编写排序函数mysort
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#include <iostream> using namespace std; struct A { int nouse; int n; A(int i):n(i) { }; A() { } }; int mysort(void * a,int n,int w, int (* compare)(const void * e1,const void * e2)) { for(int i = 0; i < n; i++) for(int j = 0; j < n - 1; j++) { char *t = (char*)a; t += j * w; if(compare(t, t + w) > 0) { for(int k = 0; k < w; k++) swap(*(t + k), *(t + w + k)); } } } int MyCompare1( const void * e1,const void * e2) { int * p1 = (int * ) e1; int * p2 = (int * ) e2; return * p1 - * p2; } int MyCompare2( const void * e1,const void * e2) { int * p1 = (int * ) e1; int * p2 = (int * ) e2; return (* p1 %10) - (* p2 % 10); } int MyCompare3( const void * e1,const void * e2) { A * p1 = (A*) e1; A * p2 = (A*) e2; return p1->n - p2->n; } int a[20]; A b[20]; int main () { int n; while(cin >> n) { for(int i = 0;i < n; ++i) { cin >> a[i]; b[i] = a[i]; } mysort(a,n,sizeof(int),MyCompare1); for(int i = 0;i < n; ++i) cout << a[i] << "," ; cout << endl; mysort(a,n,sizeof(int),MyCompare2); for(int i = 0;i < n; ++i) cout << a[i] << "," ; cout << endl; mysort(b,n,sizeof(A),MyCompare3); for(int i = 0;i < n; ++i) cout << b[i].n << "," ; cout << endl; } return 0; } |
03:看上去像多态
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#include <iostream> using namespace std; class B { private: int nBVal; public: void Print() { cout << "nBVal="<< nBVal << endl; } void Fun() {cout << "B::Fun" << endl; } B ( int n ) { nBVal = n;} }; class D : public B{ private: int nDVal; public: D(int n):B(3 * n){ nDVal = n; } void Fun(){ cout << "D::Fun" << endl; } void Print(){ B::Print(); cout << "nDVal=" << nDVal << endl; } }; int main() { B * pb; D * pd; D d(4); d.Fun(); pb = new B(2); pd = new D(8); pb -> Fun(); pd->Fun(); pb->Print (); pd->Print (); pb = & d; pb->Fun(); pb->Print(); return 0; } |
04:Fun和Do
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#include <iostream> using namespace std; class A { private: int nVal; public: void Fun() { cout << "A::Fun" << endl; }; void Do() { cout << "A::Do" << endl; } }; class B:public A { public: virtual void Do() { cout << "B::Do" << endl;} }; class C:public B { public: void Do( ) { cout <<"C::Do"<<endl; } void Fun() { cout << "C::Fun" << endl; } }; void Call( class B& p ) { p.Fun(); p.Do(); } int main() { C c; Call( c); return 0; } |
05:这是什么鬼delete
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#include <iostream> using namespace std; class A { public: A() { } virtual ~A() { cout << "destructor A" << endl; } }; class B:public A { public: ~B() { cout << "destructor B" << endl; } }; int main() { A * pa; pa = new B; delete pa; return 0; } |
06:怎么又是Fun和Do
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#include <iostream> using namespace std; class A { private: int nVal; public: void Fun() { cout << "A::Fun" << endl; }; virtual void Do() { cout << "A::Do" << endl; } }; class B:public A { public: virtual void Do() { cout << "B::Do" << endl;} }; class C:public B { public: void Do( ) { cout <<"C::Do"<<endl; } void Fun() { cout << "C::Fun" << endl; } }; void Call( A* p ) { p->Fun(); p->Do(); } int main() { Call( new A()); Call( new C()); return 0; } |
07:全面的MyString
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#include <cstdlib> #include <iostream> using namespace std; int strlen(const char * s) { int i = 0; for(; s[i]; ++i); return i; } void strcpy(char * d,const char * s) { int i = 0; for( i = 0; s[i]; ++i) d[i] = s[i]; d[i] = 0; } int strcmp(const char * s1,const char * s2) { for(int i = 0; s1[i] && s2[i] ; ++i) { if( s1[i] < s2[i] ) return -1; else if( s1[i] > s2[i]) return 1; } return 0; } void strcat(char * d,const char * s) { int len = strlen(d); strcpy(d+len,s); } class MyString { private: char *p; public: MyString(const char * s) { p = new char[strlen(s) + 1]; strcpy(p, s); } ~MyString() { if(p) delete [] p; } MyString(const MyString& a) { p = new char[strlen(a.p) + 1]; strcpy(p, a.p); } MyString(){ p = new char[1]; } char& operator[](int x){ return p[x]; } friend bool operator <(MyString a, MyString b){ return (-1 == strcmp(a.p, b.p)); } friend bool operator ==(MyString a, MyString b){ return (!strcmp(a.p, b.p)); } friend bool operator >(MyString a, MyString b){ return (1 == strcmp(a.p, b.p)); } friend ostream & operator <<(ostream & os, MyString & x){ int l = strlen(x.p); for(int i = 0; i < l; i++) os << x[i]; return os; } friend MyString operator +(MyString a, MyString b){ char *tmp = new char[strlen(a.p) + strlen(b.p) + 1]; strcpy(tmp, a.p); strcat(tmp, b.p); return MyString(tmp); } MyString operator +=(const char * c){ *this = *this + MyString(c); return *this; } char* operator ()(int x, int y){ char *tmp = new char[y]; for(int i = 0; i < y; i++) tmp[i] = p[x + i]; return tmp; } MyString & operator=(const MyString &x){ p = new char[strlen(x.p) + 1]; strcpy(p, x.p); return *this; } }; int CompareString( const void * e1, const void * e2) { MyString * s1 = (MyString * ) e1; MyString * s2 = (MyString * ) e2; if( * s1 < *s2 ) return -1; else if( *s1 == *s2) return 0; else if( *s1 > *s2 ) return 1; } int main() { MyString s1("abcd-"),s2,s3("efgh-"),s4(s1); MyString SArray[4] = {"big","me","about","take"}; cout << "1. " << s1 << s2 << s3<< s4<< endl; s4 = s3; s3 = s1 + s3; cout << "2. " << s1 << endl; cout << "3. " << s2 << endl; cout << "4. " << s3 << endl; cout << "5. " << s4 << endl; cout << "6. " << s1[2] << endl; s2 = s1; s1 = "ijkl-"; s1[2] = 'A' ; cout << "7. " << s2 << endl; cout << "8. " << s1 << endl; s1 += "mnop"; cout << "9. " << s1 << endl; s4 = "qrst-" + s2; cout << "10. " << s4 << endl; s1 = s2 + s4 + " uvw " + "xyz"; cout << "11. " << s1 << endl; qsort(SArray,4,sizeof(MyString),CompareString); for( int i = 0;i < 4;i ++ ) cout << SArray[i] << endl; //s1的从下标0开始长度为4的子串 cout << s1(0,4) << endl; //s1的从下标5开始长度为10的子串 cout << s1(5,10) << endl; return 0; } |
08:继承自string的MyString
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#include <cstdlib> #include <iostream> #include <string> #include <algorithm> using namespace std; class MyString:public string { public: MyString(){} MyString(const char* x):string(x){} MyString operator +(MyString x){ string str = (*this) + string(x); return MyString(str.c_str()); } MyString operator +(const char* x){ string str = (*this); str += x; return MyString(str.c_str()); } friend MyString operator +(const char* a, const MyString b){ MyString str; str += a + string(b); return str; } string operator()(int a, int b){ string str = ""; for(int i = 0; i < b; i++) str += (*this)[a + i]; return str; } }; int main() { MyString s1("abcd-"),s2,s3("efgh-"),s4(s1); MyString SArray[4] = {"big","me","about","take"}; cout << "1. " << s1 << s2 << s3<< s4<< endl; s4 = s3; s3 = s1 + s3; cout << "2. " << s1 << endl; cout << "3. " << s2 << endl; cout << "4. " << s3 << endl; cout << "5. " << s4 << endl; cout << "6. " << s1[2] << endl; s2 = s1; s1 = "ijkl-"; s1[2] = 'A' ; cout << "7. " << s2 << endl; cout << "8. " << s1 << endl; s1 += "mnop"; cout << "9. " << s1 << endl; s4 = "qrst-" + s2; cout << "10. " << s4 << endl; s1 = s2 + s4 + " uvw " + "xyz"; cout << "11. " << s1 << endl; sort(SArray,SArray+4); for( int i = 0;i < 4;i ++ ) cout << SArray[i] << endl; //s1的从下标0开始长度为4的子串 cout << s1(0,4) << endl; //s1的从下标5开始长度为10的子串 cout << s1(5,10) << endl; return 0; } |
09:惊呆！Point竟然能这样输入输出
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#include <iostream> using namespace std; class Point { private: int x; int y; public: Point() { }; friend istream& operator >>(istream& is, Point& p){ cin >> p.x >> p.y; return is; } friend ostream& operator <<(ostream& os, Point& p){ cout << p.x << ',' << p.y; return os; } }; int main() { Point p; while(cin >> p) { cout << p << endl; } return 0; } |
10:Big & Base 封闭类问题
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#include <iostream> #include <string> using namespace std; class Base { public: int k; Base(int n):k(n) { } }; class Big { public: int v; Base b; Big(int n):v(n),b(Base(n)){} }; int main() { int n; while(cin >>n) { Big a1(n); Big a2 = a1; cout << a1.v << "," << a1.b.k << endl; cout << a2.v << "," << a2.b.k << endl; } } |
11:看上去好坑的运算符重载
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#include <iostream> using namespace std; class MyInt { int nVal; public: MyInt( int n) { nVal = n ;} MyInt& operator-(int x){ nVal-=x; return *this; } friend int Inc(MyInt x){ return x.nVal + 1; } }; int Inc(int n) { return n + 1; } int main () { int n; while(cin >>n) { MyInt objInt(n); objInt-2-1-3; cout << Inc(objInt); cout <<","; objInt-2-1; cout << Inc(objInt) << endl; } return 0; } |
12:为啥 while(cin >> n) 能成立？
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#include <iostream> using namespace std; class MyCin { private: bool flag; public: MyCin(){ flag = 1; } MyCin& operator >> (int& p){ p = -1; if(flag)cin >> p; if(p == -1)flag = 0; return (*this); } operator bool(){ return flag; } }; int main() { MyCin m; int n1,n2; while( m >> n1 >> n2) cout << n1 << " " << n2 << endl; return 0; } |
13:这个模板并不难
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#include <iostream> #include <string> #include <cstring> using namespace std; template <class T> class myclass { int size; T *p; public: myclass(T *c, int size_){ p = new T[size_]; size = size_; for(int i = 0; i < size_; i++) p[i] = c[i]; } ~myclass( ) { delete [] p; } void Show() { for( int i = 0;i < size;i ++ ) { cout << p[i] << ","; } cout << endl; } }; int a[100]; int main() { char line[100]; while( cin >> line ) { myclass<char> obj(line,strlen(line));; obj.Show(); int n; cin >> n; for(int i = 0;i < n; ++i) cin >> a[i]; myclass<int> obj2(a,n); obj2.Show(); } return 0; } |
14:排序，又见排序!
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#include <iostream> using namespace std; bool Greater2(int n1,int n2) { return n1 > n2; } bool Greater1(int n1,int n2) { return n1 < n2; } bool Greater3(double d1,double d2) { return d1 < d2; } template <class T1,class T2> void mysort( T1 l, T1 r, T2 cmp){ for(T1 i = l; i != r; i++) for(T1 j = i + 1; j != r; j++) if(cmp(*j, *i))swap(*i, *j); } #define NUM 5 int main() { int an[NUM] = { 8,123,11,10,4 }; mysort(an,an+NUM,Greater1); //从小到大排序 for( int i = 0;i < NUM; i ++ ) cout << an[i] << ","; mysort(an,an+NUM,Greater2); //从大到小排序 cout << endl; for( int i = 0;i < NUM; i ++ ) cout << an[i] << ","; cout << endl; double d[6] = { 1.4,1.8,3.2,1.2,3.1,2.1}; mysort(d+1,d+5,Greater3); //将数组从下标1到下标4从小到大排序 for( int i = 0;i < 6; i ++ ) cout << d[i] << ","; return 0; } |
15:哭死！三维数组类模板增强版!
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#include <iostream> #include <iomanip> #include <cstring> using namespace std; template <class T> class CArray3D { class CArray2D{ private: int i, j; T* a; public: void ini(int _i, int _j){ i = _i; j = _j; a = new T[i * j]; } ~CArray2D(){ delete [] a; } T* operator[](int _i){ return a + _i * j; } operator T*(){ return this->a; } void print(int id){ cout << "layer " << id << ":" << endl; for(int x = 0; x < i; x++) { for(int y = 0; y < j; y++) cout << (*this)[x][y] << ','; cout<<endl; } } }; int k; CArray2D* a; public: CArray3D(){} ~CArray3D(){ delete [] a; } CArray3D(int _k, int _i, int _j):k(_k){ a = new CArray2D[k]; for(int i = 0; i < k; i++) a[i].ini(_i, _j); } CArray2D& operator[](int _k) { return a[_k]; } void PrintAll(){ for(int i = 0; i < k; i++) (*this)[i].print(i); } }; int main() { CArray3D<int> a(3,4,5); int No = 0; for( int i = 0; i < 3; ++ i ) for( int j = 0; j < 4; ++j ) for( int k = 0; k < 5; ++k ) a[i][j][k] = No ++; a.PrintAll(); memset(a[1],-1 ,20*sizeof(int)); a.PrintAll(); memset(a[1][1],0 ,5*sizeof(int)); a.PrintAll(); CArray3D<double> b(3,2,2); for( int i = 0; i < 3; ++ i ) for( int j = 0; j < 2; ++j ) for( int k = 0; k < 2; ++k ) b[i][j][k] = 10.0/(i+j+k+1); b.PrintAll(); return 0; } |
16:山寨版istream_iterator
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#include <iostream> #include <string> using namespace std; template <class T> class CMyistream_iterator { private: istream& ist; T now; public: CMyistream_iterator(){} CMyistream_iterator(istream &ist_):ist(ist_){ cin >> now; } T operator*(){ return now; } void operator ++(int){ cin >> now; } }; int main() { int t; cin >> t; while( t -- ) { CMyistream_iterator<int> inputInt(cin); int n1,n2,n3; n1 = * inputInt; //读入 n1 int tmp = * inputInt; cout << tmp << endl; inputInt ++; n2 = * inputInt; //读入 n2 inputInt ++; n3 = * inputInt; //读入 n3 cout << n1 << " " << n2<< " " << n3 << " "; CMyistream_iterator<string> inputStr(cin); string s1,s2; s1 = * inputStr; inputStr ++; s2 = * inputStr; cout << s1 << " " << s2 << endl; } return 0; } |
01:简单的PrintArray
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#include <iostream> #include <string> using namespace std; template <class T> void PrintArray( T a, T b) { for(T i = a; i != b; i++) cout << *i << ','; cout << endl; } int main() { string array[4] = { "Tom","Jack","Mary","John"}; PrintArray(array,array+4); int a[4] = { 1, 2, 3, 4}; PrintArray(a,a+4); return 0; } |
02:简单的SumArray
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#include <iostream> #include <string> using namespace std; template <class T> T SumArray( T* a, T* b) { T sum = *a; for(T* i = a + 1; i != b; i++) sum = sum + *i; return sum; } int main() { string array[4] = { "Tom","Jack","Mary","John"}; cout << SumArray(array,array+4) << endl; int a[4] = { 1, 2, 3, 4}; //提示：1+2+3+4 = 10 cout << SumArray(a,a+4) << endl; return 0; } |
03:简单的foreach
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#include <iostream> #include <string> using namespace std; template <class T1, class T2> void MyForeach(T1 l, T1 r, T2 f) { for(T1 i = l; i != r; i++) f(*i); } void Print(string s) { cout << s; } void Inc(int & n) { ++ n; } string array[100]; int a[100]; int main() { int m,n; while(cin >> m >> n) { for(int i = 0;i < m; ++i) cin >> array[i]; for(int j = 0; j < n; ++j) cin >> a[j]; MyForeach(array,array+m,Print); cout << endl; MyForeach(a,a+n,Inc); for(int i = 0;i < n; ++i) cout << a[i] << ","; cout << endl; } return 0; } |
04:简单的Filter
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#include <iostream> #include <string> using namespace std; template <class T1, class T2> T1 Filter(T1 l, T1 r, T1 con, T2 f) {// 返回尾指针 for(T1 i = l; i != r; i++) if(f(*i)) { *con = *i; con++; } return con; } bool LargerThan2(int n) { return n > 2; } bool LongerThan3(string s) { return s.length() > 3; } string as1[5] = {"Tom","Mike","Jack","Ted","Lucy"}; string as2[5]; int a1[5] = { 1,2,3,4,5}; int a2[5]; int main() { string * p = Filter(as1,as1+5,as2,LongerThan3); for(int i = 0;i < p - as2; ++i) cout << as2[i]; cout << endl; int * p2 = Filter(a1,a1+5,a2,LargerThan2); for(int i = 0;i < p2-a2; ++i) cout << a2[i] << ","; return 0; } |
05:goodcopy
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#include <iostream> using namespace std; template <class T> struct GoodCopy { void operator()(T* l, T* r, T* st){ T* p = new T[r - l + 2]; for(T* i = l; i != r; i++) p[i - l] = *i; for(int i = 0; i <= r - l + 1; i++) *(st + i) = p[i]; delete [] p; } }; int a[200]; int b[200]; string c[200]; string d[200]; template <class T> void Print(T s,T e) { for(; s != e; ++s) cout << * s << ","; cout << endl; } int main() { int t; cin >> t; while( t -- ) { int m ; cin >> m; for(int i = 0;i < m; ++i) cin >> a[i]; GoodCopy<int>()(a,a+m,b); Print(b,b+m); GoodCopy<int>()(a,a+m,a+m/2); Print(a+m/2,a+m/2 + m); for(int i = 0;i < m; ++i) cin >> c[i]; GoodCopy<string>()(c,c+m,d); Print(c,c+m); GoodCopy<string>()(c,c+m,c+m/2); Print(c+m/2,c+m/2 + m); } return 0; } |
06:你真的搞清楚为啥 while(cin >> n) 能成立了吗？
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#include <iostream> using namespace std; class MyCin { private: bool flag; public: MyCin(){ flag = 1; } MyCin& operator >> (int& p){ if(flag)scanf("%d", &p); if(p == -1)flag = 0; return (*this); } operator bool(){ return flag; } }; int main() { MyCin m; int n1,n2; while( m >> n1 >> n2) cout << n1 << " " << n2 << endl; return 0; } |
07:按距离排序
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#include <iostream> #include <cmath> #include <algorithm> #include <string> using namespace std; template <class T1,class T2> struct Closer { private: T1 bas; T2 f; public: Closer(){} Closer(T1 bas_, T2 f_):bas(bas_),f(f_){} bool operator()(const T1 &a, const T1 &b){ if(f(a, bas) == f(b, bas)) return a < b; else return f(a, bas) < f(b, bas); } }; int Distance1(int n1,int n2) { return abs(n1-n2); } int Distance2(const string & s1, const string & s2) { return abs((int)s1.length()- (int) s2.length()); } int a[10] = { 0,3,1,4,7,9,20,8,10,15}; string b[6] = {"American","Jack","To","Peking","abcdefghijklmnop","123456789"}; int main() { int n;string s; while( cin >> n >> s ) { sort(a,a+10,Closer<int ,int (*)(int ,int)> (n,Distance1)); for(int i = 0;i < 10; ++i) cout << a[i] << "," ; cout << endl; sort(b,b+6,Closer<string,int (*)(const string &,const string & )> (s,Distance2)); for(int i = 0;i < 6; ++i) cout << b[i] << "," ; cout << endl; } return 0; } |
08:自己实现bitset
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#include <iostream> #include <cstring> using namespace std; template <int bitNum> struct MyBitset { char a[bitNum/8+1]; MyBitset() { memset(a,0,sizeof(a));}; void Set(int i,int v) { char & c = a[i/8]; int bp = i % 8; if( v ) c |= (1 << bp); else c &= ~(1 << bp); } class A{ public: const int x; char* a; A(int _x, char *_a):x(_x), a(_a){} A& operator=(int v){ if(v)a[x / 8] |= (1 << (x % 8)); else a[x / 8] &= ~(1 << (x % 8)); return *this; } operator bool(){ return 1 & (a[x / 8] >> (x % 8)); } A& operator=(A& p){ *this = bool(p); return *this; } }; A operator[](int x){ return A(x, a); } void Print() { for(int i = 0;i < bitNum; ++i) cout << (*this) [i]; cout << endl; } }; int main() { int n; int i,j,k,v; while( cin >> n) { MyBitset<20> bs; for(int i = 0;i < n; ++i) { int t; cin >> t; bs.Set(t,1); } bs.Print(); cin >> i >> j >> k >> v; bs[k] = v; bs[i] = bs[j] = bs[k]; bs.Print(); cin >> i >> j >> k >> v; bs[k] = v; (bs[i] = bs[j]) = bs[k]; bs.Print(); } return 0; } |
09:很难蒙混过关的CArray3d三维数组模板类
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#include <iostream> #include <iomanip> #include <cstring> using namespace std; template <class T> class CArray3D { class CArray2D{ private: int i, j; T* a; public: CArray2D(){} void ini(int _i, int _j){ i = _i; j = _j; a = new T[i * j]; } ~CArray2D(){ delete [] a; } T* operator[](int _i){ return a + _i * j; } operator T*(){ return this->a; } }; private: CArray2D* a; public: CArray3D(){} ~CArray3D(){ delete [] a; } CArray3D(int _k, int _i, int _j){ a = new CArray2D[_k]; for(int i = 0; i < _k; i++) a[i].ini(_i, _j); } CArray2D& operator[](int _k) { return a[_k]; } }; CArray3D<int> a(3,4,5); CArray3D<double> b(3,2,2); void PrintA() { for(int i = 0;i < 3; ++i) { cout << "layer " << i << ":" << endl; for(int j = 0; j < 4; ++j) { for(int k = 0; k < 5; ++k) cout << a[i][j][k] << "," ; cout << endl; } } } void PrintB() { for(int i = 0;i < 3; ++i) { cout << "layer " << i << ":" << endl; for(int j = 0; j < 2; ++j) { for(int k = 0; k < 2; ++k) cout << b[i][j][k] << "," ; cout << endl; } } } int main() { int No = 0; for( int i = 0; i < 3; ++ i ) { a[i]; for( int j = 0; j < 4; ++j ) { a[j][i]; for( int k = 0; k < 5; ++k ) a[i][j][k] = No ++; a[j][i][i]; } } PrintA(); memset(a[1],-1 ,20*sizeof(int)); memset(a[1],-1 ,20*sizeof(int)); PrintA(); memset(a[1][1],0 ,5*sizeof(int)); PrintA(); for( int i = 0; i < 3; ++ i ) for( int j = 0; j < 2; ++j ) for( int k = 0; k < 2; ++k ) b[i][j][k] = 10.0/(i+j+k+1); PrintB(); int n = a[0][1][2]; double f = b[0][1][1]; cout << "****" << endl; cout << n << "," << f << endl; return 0; } |
1:高阶函数F(x)
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#include <iostream> using namespace std; template <class T1, class T2> class f{ T1 a; public: f(T1 _a):a(_a){} T2 operator()(T2 b){ return b + a; } }; int main() { cout << f<int,int>(7)(9) << endl; //16 cout << f<string,string> (" hello!")("world") <<endl; // world hello! cout << f<char,string> ('!')("world") << endl; return 0; //world! } |
2:高阶函数Combine
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#include <iostream> using namespace std; template <class T1, class T2, class T3> class combine{ T1 f; T2 g; public: combine(T1 _f, T2 _g):f(_f),g(_g){} T3 operator()(T3 x){ return f(f(x) + g(x)); } }; int main() { auto Square = [] (double a) { return a * a; }; auto Inc = [] (double a) { return a + 1; }; cout << combine<decltype(Square),decltype(Inc),int>(Square,Inc)(3) << endl; cout << combine<decltype(Inc),decltype(Square),double>(Inc,Square)(2.5) << endl; return 0; } |
3:实现sharedptr
每个类用一段地址记录 cnt，派生类的 cnt 地址继承基类并将其 +1，改变类中指针的时候 new 一段新的 cnt 地址，原来的保留
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#include <iostream> using namespace std; //#define MySharedPtr shared_ptr template <class T> struct MySharedPtr { mutable int* cnt; T *p; void dec(){ if(cnt) { (*cnt)--; if(*cnt == 0 && p)(*p).~T(); } } void set(){ cnt = new int; *cnt = 1; } MySharedPtr(const MySharedPtr& a){ p = a.p; cnt = a.cnt; (*cnt)++; } MySharedPtr(T* _p){ set(); p = _p; } MySharedPtr(){ cnt = NULL; p = NULL; } ~MySharedPtr(){ dec(); } void operator=(const MySharedPtr& a){ p = a.p; cnt = a.cnt; (*cnt)++; } void reset(T* _p = NULL){ dec(); set(); p = _p; } T* get(){return p;} T* operator->(){return p;} T& operator*(){return *p;} operator bool(){return (p != NULL);} }; struct A { int n; A(int v = 0):n(v){ } ~A() { cout << n << " destructor" << endl; } }; int main() { MySharedPtr<A> sp1(new A(2)); MySharedPtr<A> sp2(sp1); cout << "1)" << sp1->n << "," << sp2->n << endl; MySharedPtr<A> sp3; A * p = sp1.get(); cout << "2)" << p->n << endl; sp3 = sp1; cout << "3)" << (*sp3).n << endl; sp1.reset(); if( !sp1 ) cout << "4)sp1 is null" << endl; //会输出 A * q = new A(3); sp1.reset(q); // cout << "5)" << sp1->n << endl; MySharedPtr<A> sp4(sp1); MySharedPtr<A> sp5; sp5.reset(new A(8)); sp1.reset(); cout << "before end main" <<endl; sp4.reset(); cout << "end main" << endl; return 0; //程序结束，会delete 掉A(2) } |
计数器 9786105
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