Question

#include <iostream>
using namespace std;

int strlength(char *str)
{
    int length = 0;
    int index = 0;
    while (*(str + index)) {
        length++;
        index++;
    }
    return length;
}

char *mergeSortedStrings(char str1[], char str2[])
{   //get the length of the newstring
    int str1len = strlength(str1);
    int str2len = strlength(str2);
    int newStringlen = str1len + str2len;
    char *newString= new char[newStringlen];
    int i, j = 0;
    char temp;
    // copy str2 to the end of str1
    for (i = strlength(str1); i<256; i++)
    {
        str1[i] = str2[j];
        j++;
    }

    for (i=0; i<newStringlen;i++)
        for (j = newStringlen - 1; j > i; j--) {
            if (str1[j - 1] > str1[j])
            {
                temp = str1[j];
                str1[j] = str1[j - 1];
                str1[j - 1] = temp;

            }
        }
    str1[newStringlen] = '\0';
    return str1;
}


void main()
{
    char str1[20];
    char str2[20];

    cout << "Input string 1: ";
    cin >> str1;
    cout << "Input string 2: ";
    cin >> str2;

    cout << "The merged string is: " << mergeSortedStrings(str1, str2) << endl;
}

这是C ++字符串合并和排序编程，不使用字符串库函数。当我使用for循环将最终str1的内容复制到newString时，它没有给出正确的结果，因此我只使用了str1作为结果。它以某种方式给出了正确的结果，但我认为这可能效率不高。你能帮帮我吗？

Answer 1

这是一个如何使用自定义String类来完成它的示例。如果您不明白发生了什么，我建议您查看：NULL terminated string，copy constructor，operator overloading。 请注意，这只是一个示例，可以让您了解如何解决问题，可能会出现一些错误。

#include <iostream>

using namespace std;

class String
{
    private:
        char *_str;
        int _len;

    public:
        String()
        {
            _str = NULL;
            _len = 0;
        }

        ~String()
        {
            if (_str != NULL)
                delete _str;
        }

        String(const char *str)
        {
            _str = NULL;
            _len = 0;

            if (str == NULL) return;

            int i;
            for (i = 0; str[i] != '\0'; i++);
            _len = i;

            _str = new char[_len];

            for (i = 0; i < _len; i++)
                _str[i] = str[i];
        }

        String(const String &s)
        {
            _str = NULL;
            _len = 0;

            if (s._len == 0) return;

            _str = new char[s._len];
            _len = s._len;

            for (int i = 0; i < _len; i++)
                _str[i] = s._str[i];
        }

        //constructor for concatenation
        String(const char* a, const char* b)
        {
            _str = NULL;
            _len = 0;

            if (a == NULL || b == NULL)
                return;

            int lenA;
            for (lenA = 0; a[lenA] != '\0'; lenA++);

            int lenB;
            for (lenB = 0; b[lenB] != '\0'; lenB++);

            _len = lenA + lenB;
            _str = new char[_len];

            for (int i = 0; i < lenA; i++)
                _str[i] = a[i];

            for (int i = 0; i < lenB; i++)
                _str[lenA + i] = b[i];
        }

        int getLength() const { return _len; }
        operator const char*() { return _str; }     

        void operator=(const char* str) 
        { 
            _str = NULL;
            _len = 0;

            if (str == NULL) return;

            int i;
            for (i = 0; str[i] != '\0'; i++);
            _len = i;

            if (_str != NULL)
                delete _str;

            _str = new char[_len];

            for (i = 0; i < _len; i++)
                _str[i] = str[i];
        }

        String operator+(const char* str)
        {
            return String(*this, str);
        }

        bool operator==(const char* str)
        {
            int len;
            for (len = 0; str[len] != '\0'; len++);

            if (len != _len) return false;

            for (int i = 0; i < len; i++)
                if (str[i] != _str[i])
                    return false;

            return true;
        }

        bool operator<(const char* str)
        {
            int i;          
            for (i = 0; i < _len && str[i] != '\0'; i++)
            {
                if (_str[i] < str[i])
                    return true;
                else if (_str[i] > str[i])
                    return false;
            }

            return false;
        }

        bool operator<=(const char* str)
        {
            int i;          
            for (i = 0; i < _len && str[i] != '\0'; i++)
            {
                if (_str[i] < str[i])
                    return true;
                else if (_str[i] > str[i])
                    return false;
            }

            return (i == _len);
        }


        bool operator>(const char* str)
        {
            int i;          
            for (i = 0; i < _len && str[i] != '\0'; i++)
            {
                if (_str[i] > str[i])
                    return true;
                else if (_str[i] < str[i])
                    return false;
            }

            return (_len > i);
        }

        bool operator>=(const char* str)
        {
            int i;          
            for (i = 0; i < _len && str[i] != '\0'; i++)
            {
                if (_str[i] > str[i])
                    return true;
                else if (_str[i] < str[i])
                    return false;
            }

            return (_len >= i);
        }

        friend istream& operator>>(istream &is, String &s)
        {
            char str[512];
            is.getline(str, 512);

            s = str;

            return is;
        }
};

int main()
{

    String str1;
    String str2;


    cout << "Input string 1: ";
    cin >> str1;
    cout << "Input string 2: ";
    cin >> str2;

    String sortedMerged = str1 <= str2 ? str1 + str2 : str2 + str1;

    cout << sortedMerged;


    return 0;
}

c ++ cstring在不使用字符串库的情况下合并和排序编程

1 个答案: