#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
{
public:
char* mystr = NULL;
MyString() :mystr(new char[1]) { mystr[0] = 0; } //0 为空NULL
MyString(const char * ch) {
if (mystr != NULL) {
delete[] mystr;
}
mystr = new char[strlen(ch) + 1];
strcpy(mystr, ch);
}
MyString(const MyString& str) {
if (mystr != NULL) {
delete[] mystr;
}
mystr = new char[strlen(str.mystr) + 1];
strcpy(mystr, str.mystr);
}
MyString & operator= (const MyString & nstr) {
if (mystr != NULL) {
delete[] mystr;
}
mystr = new char[strlen(nstr.mystr) + 1];
strcpy(mystr, nstr.mystr);
return *this;
}
MyString& operator= (const char * nstr) {
if (mystr != NULL) {
delete[] mystr;
}
mystr = new char[strlen(nstr) + 1];
strcpy(mystr, nstr);
return *this;
}
MyString operator+ (const MyString& nstr) {
MyString ss;
ss.mystr = new char[strlen(nstr.mystr)+strlen(mystr) + 1];
strcpy(ss.mystr, mystr);
strcat(ss.mystr, nstr.mystr);
return ss;
}
MyString operator+ (const char* nstr) {
MyString ss;
ss.mystr = new char[strlen(nstr) + strlen(mystr) + 1];
strcpy(ss.mystr, mystr);
strcat(ss.mystr, nstr);
return ss;
}
friend MyString operator+ (const char* astr,const MyString& nstr) {
MyString ss;
ss.mystr = new char[strlen(nstr.mystr) + strlen(astr) + 1];
strcpy(ss.mystr, astr);
strcat(ss.mystr, nstr.mystr);
return ss;
}
MyString & operator+= (const char* nstr) {
strcat(mystr, nstr);
return * this;
}
char & operator[] (int index) {
return mystr[index];
}
~MyString() {
if (mystr != NULL) {
delete[] mystr;
}
}
char * operator()(int x,int len) {
static char* res = new char[len];
for (int i = 0;i < len; ++i) {
res[i] = mystr[i + x];
}
res[len] = '\0';
return res;
}
bool operator<(const MyString & b){
return mystr[0]<b.mystr[0];
}
bool operator>(const MyString & b){
return mystr[0]>b.mystr[0];
}
bool operator== (const MyString & b){
return mystr[0]==b.mystr[0];
}
operator char* () {
return mystr;
}
};
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;
}