C++ 替换字符串中的单词(文本文件)

Question

所以我在我的程序上工作，现在我无法找到解决方案。我需要在 fext 文件中替换更多的符号，目前程序只将“TIT”替换为代码“*245$a”，如果我想用同样的方式替换其他字母，程序不会改变。有人知道如何在文本文件中实现更多替换吗？让我知道是否有更好的选择可以将 5 个以上的标志替换为另一个标志。谢谢

#include <fstream>
#include <fstream>
#include <iostream>
#include <string>
using namespace std;


int main()
{

    char dateiname[64], kommando[64];

    ifstream iStream;

    cout << "Choose an activity" << endl <<
    " s - search " << endl <<
    " c - convert" << endl <<
    " * - end program" << endl;
    cin.getline(kommando,64,'\n');
    switch(kommando[0])
    {
        case 'c':
            cout << "Enter a text file!" << endl;
            cin.getline(dateiname,64,'\n');
            iStream.open("C://users//silita//desktop//schwarz.txt");

        case 's':
            break;
        case '*':
            return 0;
        default:
            cout << "I can not read " << kommando << endl;
    }

    if (!iStream)
    {
        cout << "The File" << dateiname << "does not exist." << endl;
    }

    string s;
    char o[] = "TIT";
    while (getline(iStream, s))
    {
        while(s.find(o, 0) < s.length())
            s.replace(s.find(o, 0), s.length() - s.find(o, 3),"*245$a");

        cout << s << endl;
    }

    iStream.close();
}

Answer 1

您可以使用 map在 C++ STL 中存储多个转换规则:

#include<map>
#include<algorithm>
using namespace std;

map<string,string> convertRules;
typedef map<string,string>::iterator MIT;

void setConvertRules(int numOfRules){
    string word,code;
    for(int i = 0 ; i < numOfRules; ++i){
        cin>>word>>code;

        //Use code as search key in order to decrypt
        //If you want to encrypt, use convertrules[word] = code;
        convertRules[code] = word;
    }
}

要转换一个文件，只需按如下方式进行(有些函数和类需要先声明和实现，但这里我们主要关注顶层设计):

/* Detailed class implementations are omitted for simplicity */

//a class to store contents of a file
class File;

//a processor to read, insert and overwrite certain file
class FileProcessor;

void FileProcessor::convert(const string &code, const string &word){
    cursor == file.begin();
    while(cursor != fp.end()){
         _fp.convertNextLine(code,word);
    }
}

File file;
FileProcessor filePcr;

int main()

    const string sourceDir = "C://users//silita//desktop//schwarz.txt";
    const string destDir = "C://users//silita//desktop//schwarz_decrypted.txt";

    //Open a .txt file and read in its contents
    if (!file.openAndReadIn(sourceDir)){
        cerr << "The File" << sourceDir << "does not exist." << endl;
        abort();
    }

    //Try to link processor to open file
    if(!fp.linkTo(file)){
        cerr << "Access to file" << sourceDir << "is denied." << endl;
        abort();
    }

    //iterator is like a more safe version of C-style pointer
    //the object type is a string-string pair
    for(MIT it = convertRules.begin(); it != convertRules.end(); ++it){
        fp.convert(it->first, it->second);
    }

    file.saveAs(destDir);
    return 0;
}

最后，如果我建议你使用 C 风格 strstr在处理大文件或批处理时提高效率的功能。 string::find 采用简单的顺序搜索策略，而 strstr 使用著名的 KMP algorithm 实现对于 fast pattern match in strings ，既高效又彻底(可以一次性替换所有匹配项，而不是另一个 for 循环)。