# 字符串处理器

纯模拟，但情况比较多，非常容易空指针异常。

大家要注意，边界问题以及负数问题。

整体代码如下：

#include<bits/stdc++.h>
using namespace std;
 int main() {
     int index = 0;
     long long optNum;
     string s;
     string cmd;
     while(cin >> cmd){
         //cout << s << endl;
        if(cmd == "insert") {
            string buff;
            cin >> buff;
            s.insert(index, buff);
            index += buff.size();
        }
        else if(cmd == "move") {
            cin >> optNum;
            if(optNum > 0 && index + optNum <= s.size()) index += optNum;
            if(optNum < 0 && index >= -optNum) index += optNum;
        }
        else if(cmd == "delete") {
            cin >> optNum;
            if(index >= optNum && optNum > 0){
                s.erase(index - optNum, optNum);
                index -= optNum;
            }
        }
        else if(cmd == "copy") {
            if(index > 0) {
                string tmp = s.substr(0, index);
                s.insert(index, tmp);
            }
        }
        else if(cmd == "end") {
            for(int i = 0; i < index; i++) {
                cout << s[i];
            }
            cout << '|';
            for(int i = index; i < s.size(); i++) cout << s[i];

            break;
        }
     }
     return 0;
}

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# 其他语言版本

# Java

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        StringBuilder s = new StringBuilder();
        int index = 0;
        int optNum;

        while (true) {
            String cmd = scanner.next();
            if (cmd.equals("insert")) {
                String buff = scanner.next();
                s.insert(index, buff);
                index += buff.length();
            } else if (cmd.equals("move")) {
                optNum = scanner.nextInt();
                if (optNum > 0 && index + optNum <= s.length()) index += optNum;
                if (optNum < 0 && index >= -optNum) index += optNum;
            } else if (cmd.equals("delete")) {
                optNum = scanner.nextInt();
                if (index >= optNum && optNum > 0) {
                    s.delete(index - optNum, index);
                    index -= optNum;
                }
            } else if (cmd.equals("copy")) {
                if (index > 0) {
                    String tmp = s.substring(0, index);
                    s.insert(index, tmp);
                }
            } else if (cmd.equals("end")) {
                System.out.print(s.substring(0, index) + '|' + s.substring(index));
                break;
            }
        }
        scanner.close();
    }
}

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# Python

def main():
    import sys
    input = sys.stdin.read
    data = input().split()
    s = ""
    index = 0
    i = 0

    while i < len(data):
        cmd = data[i]
        i += 1
        if cmd == "insert":
            buff = data[i]
            i += 1
            s = s[:index] + buff + s[index:]
            index += len(buff)
        elif cmd == "move":
            optNum = int(data[i])
            i += 1
            if optNum > 0 and index + optNum <= len(s):
                index += optNum
            elif optNum < 0 and index >= -optNum:
                index += optNum
        elif cmd == "delete":
            optNum = int(data[i])
            i += 1
            if index >= optNum and optNum > 0:
                s = s[:index - optNum] + s[index:]
                index -= optNum
        elif cmd == "copy":
            if index > 0:
                tmp = s[:index]
                s = s[:index] + tmp + s[index:]
        elif cmd == "end":
            print(s[:index] + '|' + s[index:])
            break

if __name__ == "__main__":
    main()

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