34-数组操作符[]的重载

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1、

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可以

#include <iostream>#include <string>using namespace std;int main(){    string s = "a1b2c3d4e";    int n = 0;    for(int i = 0; i<s.length(); i++)    {        if( isdigit(s[i]) )        {            n++;        }    }    cout << n << endl;    return 0;}

2、

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3、

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#include <iostream>#include <string>using namespace std;int main(){    int a[5] = {0};    for(int i=0; i<5; i++)    {        a[i] = i;    }    for(int i=0; i<5; i++)    {        cout << *(a + i) << endl;    // cout << a[i] << endl;    }    cout << endl;    for(int i=0; i<5; i++)    {        i[a] = i + 10;    // a[i] = i + 10;    }    for(int i=0; i<5; i++)    {        cout << *(i + a) << endl;  // cout << a[i] << endl;    }    return 0;}

4、

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#include <iostream>#include <string>using namespace std;class Test{    int a[5];public:    int& operator [] (int i)    {        return a[i];    }    int& operator [] (const string& s)    {        if( s == "1st" )        {            return a[0];        }        else if( s == "2nd" )        {            return a[1];        }        else if( s == "3rd" )        {            return a[2];        }        else if( s == "4th" )        {            return a[3];        }        else if( s == "5th" )        {            return a[4];        }        return a[0];    }    int length()    {        return 5;    }};int main(){    Test t;    for(int i=0; i<t.length(); i++)    {        t[i] = i;    }    for(int i=0; i<t.length(); i++)    {        cout << t[i] << endl;    }    cout << t["5th"] << endl;    cout << t["4th"] << endl;    cout << t["3rd"] << endl;    cout << t["2nd"] << endl;    cout << t["1st"] << endl;    return 0;}

5、

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6、数组类

#ifndef _INTARRAY_H_#define _INTARRAY_H_class IntArray{private:    int m_length;    int* m_pointer;    IntArray(int len);    IntArray(const IntArray& obj);    bool construct();public:    static IntArray* NewInstance(int length);     int length();    bool get(int index, int& value);    bool set(int index ,int value);    int& operator [] (int index);    IntArray& self();    ~IntArray();};#endif

#include "IntArray.h"IntArray::IntArray(int len){    m_length = len;}bool IntArray::construct(){    bool ret = true;    m_pointer = new int[m_length];    if( m_pointer )    {        for(int i=0; i<m_length; i++)        {            m_pointer[i] = 0;        }    }    else    {        ret = false;    }    return ret;}IntArray* IntArray::NewInstance(int length) {    IntArray* ret = new IntArray(length);    if( !(ret && ret->construct()) )     {        delete ret;        ret = 0;    }    return ret;}int IntArray::length(){    return m_length;}bool IntArray::get(int index, int& value){    bool ret = (0 <= index) && (index < length());    if( ret )    {        value = m_pointer[index];    }    return ret;}bool IntArray::set(int index, int value){    bool ret = (0 <= index) && (index < length());    if( ret )    {        m_pointer[index] = value;    }    return ret;}int& IntArray::operator [] (int index){    return m_pointer[index];}IntArray& IntArray::self(){    return *this;}IntArray::~IntArray(){    delete[]m_pointer;}

#include <iostream>#include <string>#include "IntArray.h"using namespace std;int main(){    IntArray* a = IntArray::NewInstance(5);        if( a != NULL )    {        IntArray& array = a->self();        cout << "array.length() = " << array.length() << endl;        array[0] = 1;        for(int i=0; i<array.length(); i++)        {              cout << array[i] << endl;        }    }    delete a;    return 0;}

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