程式設計與演算法三第五週測驗finish
1:全面的MyString
#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 {//補充程式碼 }; 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的從下標0開始長度為4的子串 cout << s1(0,4) << endl; //s1的從下標5開始長度為10的子串 cout << s1(5,10) << endl; return 0; }
輸入
無
輸出
1. abcd-efgh-abcd-
2. abcd-
3.
4. abcd-efgh-
5. efgh-
6. c
7. abcd-
8. ijAl-
9. ijAl-mnop
10. qrst-abcd-
11. abcd-qrst-abcd- uvw xyz
about
big
me
take
abcd
qrst-abcd-
#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 { // 在此處補充你的程式碼 char *p; public: MyString(const char* p1) { if (!p1) { p = NULL; return; } p = new char[strlen(p1) + 1]; strcpy(p, p1); } MyString(const string &p1) { p = new char[strlen(p1.c_str()) + 1]; strcpy(p, p1.c_str()); } MyString() { p = NULL; } MyString(const MyString &a) { if (this == &a) return; if (!a.p) { p = NULL; return; } p = new char[strlen(a.p) + 1]; strcpy(p, a.p); } friend ostream& operator<<(ostream& o, MyString &a) { if(!a.p) return o; o << a.p; return o; } friend MyString operator+(const MyString& a,const MyString& b){ MyString c; c.p=new char[strlen(a.p)+strlen(b.p)+1]; strcpy(c.p,a.p); strcat(c.p,b.p); return c; } char& operator[](int x){//這個好好琢磨下,char*不可以 return p[x]; } MyString& operator+=(const string &p1){ if(!p){ p = new char[strlen(p1.c_str()) + 1]; strcpy(p, p1.c_str()); return *this; }else{ char *p2=new char[strlen(p1.c_str())+strlen(p)+1]; strcpy(p2,p); strcat(p2,p1.c_str()); delete []p; p=new char[strlen(p2)]; strcpy(p,p2); return *this; } } friend MyString operator+(const char* a,const MyString& b){ MyString a1(a); MyString c=a1+b; return c; } bool operator<(MyString &b){ if(strcmp(p,b.p)==-1){ return true; }else return false; } bool operator==(MyString &b){ if(strcmp(p,b.p)==0){ return true; }else return false; } int operator>(MyString &b){ if(strcmp(p,b.p)){ return true; }else return false; } MyString& operator()(int s,int e){//注意這裡的引用 MyString x; x.p=new char[e-s+1]; int j=0; for(int i=s;i<e;i++){ x.p[j++]=p[i]; } x.p[e-s]=0; return x; } }; 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的從下標0開始長度為4的子串 cout << s1(0, 4) << endl; //s1的從下標5開始長度為10的子串 cout << s1(5, 10) << endl;/**/ getchar(); return 0; }
知識點:
語法:
const char *c_str();
c_str()函式返回一個指向正規C字串的指標, 內容與本string串相同.
這是為了與c語言相容,在c語言中沒有string類型,故必須通過string類物件的成員函式c_str()把string 物件轉換成c中的字串樣式。
注意:一定要使用strcpy()函式 等來操作方法c_str()返回的指標
比如:最好不要這樣:
char* c;
string s="1234";
c = s.c_str(); //c最後指向的內容是垃圾,因為s物件被析構,其內容被處理
應該這樣用:
char c[20];
string s="1234";
strcpy(c,s.c_str());
這樣才不會出錯,c_str()返回的是一個臨時指標,不能對其進行操作
再舉個例子
c_str() 以 char* 形式傳回 string 內含字串
如果一個函式要求char*引數,可以使用c_str()方法:
string s = "Hello World!";
printf("%s", s.c_str()); //輸出 "Hello World!"
2:繼承自串的MyString
描述
程式填空,輸出指定結果
#include <cstdlib>
#include <iostream>
#include <string>
#include <algorithm>
using namespace std;
class MyString:public string
{
//補充程式碼
};
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的從下標0開始長度為4的子串
cout << s1(0,4) << endl;
//s1的從下標5開始長度為10的子串
cout << s1(5,10) << endl;
return 0;
}
輸入
無
輸出
1. abcd-efgh-abcd-
2. abcd-
3.
4. abcd-efgh-
5. efgh-
6. c
7. abcd-
8. ijAl-
9. ijAl-mnop
10. qrst-abcd-
11. abcd- qrst-abcd- uvw xyz
關於
大
我
採取
abcd
qrst-abcd-
原理參考:
#include<iostream>
using namespace std;
class A{
public:
int x;
A(int n):x(n){ }
Print(){
cout<<x;
}
};
class B:public A{
public:
B(int n):A(n){ }
};
int main(){
B b(10);
b.Print();//B裡面沒有的函式,會自動呼叫A的
}
#include <cstdlib>
#include <iostream>
#include <string>
#include <algorithm>
using namespace std;
class MyString :public string
{
// 在此處補充你的程式碼
public:
MyString() :string() {}
MyString(const char *c) :string(c) {}
MyString(const string &s) :string(s) {}//這一句是核心,"abcd-"這裡是string物件
MyString operator()(int i, int j) {
/*string b = string::substr(i, j);
MyString a(b);//或者下面的寫法*/
MyString a(string::substr(i, j));
//or MyString a(this->substr(i, j));
//or return MyString(substr(s, e));
return a;
}
};
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;
s1 + 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的從下標0開始長度為4的子串
cout << s1(0,4) << endl;
//s1的從下標5開始長度為10的子串
cout << s1(5,10) << endl;
getchar();
return 0;
}