【实验5】c++MyString类实现

ccnu_hupo_cpp_class_tst6exercise2_by:lele_2013_10_30

new不忘delete

Design the string class in the C++ library by providing your own implementation for the following functions (name your class MyString):

MyString();//构造

MyString(const char* cString);//地址不能变

char at(int index) const;//输入数组下标，返回字符

int length() const;//长度

void clear();//清空len=0

bool empty() const;//是否清空？len不变

int compare(const MyString& s) const;//

int compare(int index, int n, const MyString& s) const;

void copy(char s[], int index, int n);

char* data() const;

int find(char ch) const;

int find(char ch, int index) const;

int find(const MyString& s, int index) const;

*/

#include

#include

using namespace std;

class MyString

{

public:

MyString();

MyString(const char* cString);

char at(int index) const;//

int length() const;

void clear();

bool empty() const;

int compare(const MyString& s) const;

int compare(int index, int n, const MyString& s) const;

void copy(char s[], int index, int n);

char* data() const;

int find(char ch) const;

int find(char ch, int index) const;

int find(const MyString& s, int index) const;

~MyString()

cout<<"delete..."<

delete []a;

}

private:

char *a;

int len;

};

MyString::MyString(const char* cString)

{

if (cString==NULL)

{

a=new char[1];

a[0]=0;

int len=0;

}

else

{

a=new char [strlen(cString)+1];

strcpy(a,cString);

len=strlen(cString);

}

}

char MyString::at(int index) const

{

if(len==0)

{cout<<"no char in string"<

return 0;

}

if(index>len)

{

cout<<"the maximun array exceed"<

return 0 ;

}

else

{

return a[index-1];

}

}

int MyString::length() const

return len;

}

void MyString::clear()

{

if(!a)

{

delete []a;

a=NULL;

}

len=0;

//a=" ";

}

bool MyString::empty() const

{

if(len==0)

return true;

else

return false;

}

int MyString::compare(const MyString& s) const

{

int m=this->len;int n=s.len;

for(int i=0;i

{

if(s.a[i]==a[i])

continue;

else if(s.a[i]

return 1;

else

return -1;

}

return 0;

}

int MyString::compare(int index, int n, const MyString& s) const {

int m=len,k=s.len;

if(index+n>m||index+n>k)

{

cout<<"cannot compare!"<

///I dont know how to solve it

}

for(int i=index-1,j=0;i

{

if(s.a[j]==a[i])

continue;

else if(s.a[j]

return 1;

else

return -1;

}

return 0;

}

void MyString::copy(char s[], int index, int n) {

if(n>=len)

{cout<<"the maximun array exceed"<len)

{

cout<<"the maximun array exceed"<

return;

}

else

{

for(int i=n-1,j=0;i

s[j]=a[i];

}

}

char* MyString::data() const

{

return a;

}

int MyString::find(char ch) const

{

for(int i=0;i

{

if(ch==a[i])

return i+1;

}

return 0;

}

int MyString::find(char ch, int index) const

{

if(index>len||index<1)

{

cout<<"the index num is should be 1~ "<

return 0;

}

for(int i=index-1;i

{

if(ch==a[i])

return i+1;

}

return -1;

}

int MyString::find(const MyString& s, int index) const

{

if(index>s.len||index<1)

{

cout<<"the index num is should be 1~ "<

return 0;

}

char ch=s.a[index-1];

for(int i=0;i

{

if(ch==a[i])

return i+1;

}

return 0;

}