专题：字符串

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1.字符串的替换

#include <iostream>
using namespace std;

void strcopy(char *des, char *src)      //字符串的复制
{
    while (*des++ = *src++);
}

char* mystrcat(char *src1, char *src2, char *res)   //字符串的连接
{
    int src1_len = strlen(src1);
    int src2_len = strlen(src2);
    res = new char[src1_len + src2_len];
    for (int i = 0; i < src1_len; i++)
    {
        res[i] = src1[i];
    }
    for (int i = 0; i < src2_len; i++)
    {
        res[i + src1_len] = src2[i];
    }
    res[src1_len + src2_len] = '\0';
    return res;
}

char* StrReplace(char *strSrc, char *strFind, char *strReplace)
{
    int strFind_len = strlen(strFind);
    int strReplace_len = strlen(strReplace);
    int i;
    for (i = 0; i <strlen(strSrc); i++)
    {
        int strcompare = strncmp(strSrc + i, strFind, strFind_len);
        if (strcompare == 0)
        {
            int strSrc_len = strlen(strSrc);
            int remainlen = strSrc_len - i - strFind_len;
            char *temp = new char[remainlen];           //存储strSrc的strFind之后的后部分的字符
            strcopy(temp, strSrc + i + strFind_len);
            cout << "temp:::" << temp << endl;          
            char *result = new char[i];                 //存储strSrc的strFind之后的前部分的字符
            for (int j = 0; j < i; j++)
                result[j] = strSrc[j];
            result[i] = '\0';                   //这个表示字符串的结束，很重要！！！
            char *result1 = new char[i + strReplace_len];       //result1:用于存储strSrc在strFind的前部分的字符以及strReplace
            result1 = mystrcat(result, strReplace, result1);
            cout << ".............." << result1 << endl;
            strSrc = new char[i + strReplace_len + remainlen];
            strSrc = mystrcat(result1, temp, strSrc);           //用于存放替换后的字符
            strSrc[i + strReplace_len + remainlen] = '\0';      //标识字符的结束

    //      StrReplace(newstrSrc, strFind, strReplace);
        }
    }
    return strSrc;
}

int main()
{
    char *strSrc = "RSTABCDEFGHIJKLMNOPQRSTUVWRSTXYZRST";
    char *strFind = "RST";
    char *strReplace = "12345";
    //  StrReplace(strSrc, strFind, strReplace);
    int n = strlen(strSrc);
    cout << n << endl;
    strSrc = StrReplace(strSrc, strFind, strReplace);
    cout << endl;
    cout << strSrc << endl;
    cout << endl;

    /*用于做测试子过程部分的代码
    char *res1 = new char[strlen(strFind)];
    strcopy(res1, strFind);
    cout << res1 << endl;
    char *res = new char[strlen(strFind) + strlen(strReplace)];
    res = mystrcat(strFind, strReplace, res);
    res[strlen(strFind) + strlen(strReplace)] = '\0';
    cout << res << endl;
    */

    system("pause");
    return 0;
}

2.字符串的反转

把”cba” 称为 “abc”的反转串

public class ReverseString {
    public static String reverse(String s){
        if (s.length() < 2 || s == null)
            return s;
        else
            return reverse(s.substring(1)) + s.charAt(0);
    }
    public static void main(String[] args){
        String s = "123456";
        String ss = reverse(s);
        System.out.println(ss);
    }

!后面会陆续更新这个课题的