【C++面向对象练习】实现简单的string
程序设计与算法(三) 019 全面的MyString
学C++的过程中,每看到自己前一天写的代码,都会感觉这是什么gs玩意。。
//
// Created by vv123 on 2022/3/22.
//
#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
{
char* str = NULL;
public:
MyString(): str(new char[1]) { str[0] = 0; }
MyString(const char* s) {
delete[] str;
str = new char[strlen(s) + 1];
strcpy(str, s);
}
MyString(const MyString& s) {
delete[] str;
str = new char[strlen(s.str) + 1];
strcpy(str, s.str);
}
MyString& operator=(const char* s) {
delete[] str;
str = new char[strlen(s) + 1];
strcpy(str, s);
return *this;
}
MyString& operator=(const MyString& s) {
if (&s == this) return *this;
if (str) delete[] str;
str = new char[strlen(s.str) + 1];
strcpy(str, s.str);
return *this;
}
MyString operator+ (const MyString& s) {
MyString res;
res.str = new char[strlen(str) + strlen(s.str) + 1];
strcpy(res.str, str);
strcat(res.str, s.str);
return res;
}
friend MyString operator+(const char* str, const MyString& s) {
MyString res;
res.str = new char[strlen(str) + strlen(s.str) + 1];
strcpy(res.str, str);
strcat(res.str, s.str);
return res;
}
MyString& operator+=(const char* s) {
strcat(str, s);
return *this;
}
char& operator[](int i) {
return str[i];
}
char* operator()(int pos, int len) {
char* res = new char[len + 1];
for (int i = 0; i < len; i++)
res[i] = str[pos + i];
res[len] = '\0';
return res;
}
bool operator<(const MyString& s) {
return strcmp(str, s.str) < 0;
}
bool operator>(const MyString& s) {
return strcmp(str, s.str) > 0;
}
bool operator==(const MyString& s) {
return strcmp(str, s.str) == 0;
}
friend ostream& operator<<(ostream& os, const MyString& s) {
os << s.str;
return os;
}
~MyString() { delete[] str; }
};
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;
}