實現說明:字符串類String的簡單實現,內部採用字符數組實現
運行平臺:VS2010
參考:http://rsljdkt.iteye.com/blog/770072
經驗說明:拷貝構造函數、重載賦值運算符、實現析構函數三個操作在實現自定義類時往往同時出現。
#include <iostream>
usingnamespace std;
class String{
public:
String(constchar *str = NULL);//默認構造函數
String(const String &str);//複製構造函數
~String();//析構函數
String operator+(const String & str);//字符串連接
String & operator=(const String &str);//字符串賦值
bool operator==(const String &str);//判斷是否字符串相等
int Length();//獲取字符串長度
friend ostream & operator<<(ostream &o,const String &str);//重載輸出
String SubStr(int start, int end);//求子字符串(start ... end-1)
private:
char * charArray;
};
String::String(constchar *str)
{
if(str == NULL){
charArray=newchar[1];
charArray[0]='\0';
}else{
charArray=newchar[strlen(str)+1];
strcpy(charArray,str);
}
}
String::String(const String &str)
{
charArray = newchar[strlen(str.charArray)+1];
strcpy(charArray,str.charArray);
}
String::~String()
{
delete [] charArray;
}
String String::operator+(const String &str)
{
String res;
delete [] res.charArray;//釋放原有空間
res.charArray = newchar[strlen(charArray)+strlen(str.charArray)+1];
strcpy(res.charArray,charArray);
strcpy(res.charArray+strlen(charArray),str.charArray);
return res;
}
String & String::operator=(const String &str)
{
if(charArray == str.charArray)
return *this;
delete [] charArray;
charArray = newchar[strlen(str.charArray)+1];
strcpy(charArray,str.charArray);
return *this;
}
bool String::operator==(const String &str)
{
return strcmp(charArray,str.charArray) == 0;
}
int String::Length()
{
return strlen(charArray);
}
ostream & operator<<(ostream &o, const String &str)
{
o<<str.charArray;
return o;
}
String String::SubStr(int start, int end)
{
String res;
delete [] res.charArray;//釋放原有內存
res.charArray = newchar[end-start+1];//重新申請內存
for(int i=0; i+start<end; i++){
res.charArray[i]=charArray[start+i];
}
res.charArray[end-start] = '\0';
return res;
}
void test()
{
String s = "abcd";
String t = "abcd";
cout<<s<<(s==t?" == ":" != ")<<t<<endl;
String s2 = "Hello ";
String s3 = "China!";
cout<<s2+s3<<endl;
cout<<(s2+s3).SubStr(0,s2.Length()+s3.Length())<<endl;
}
int main()
{
test();
system("pause");
}
運行結果:
abcd == abcd
Hello China!
Hello China!
請按任意鍵繼續. . .