To Extract data from text file using c++98 linux

Question

I am trying extract some lines from plain text file. where it contains list of shell script executables with some generic keys for that particular sh file. the required data need to extract from that file should exclude .sh file name and MH_TEST keys.

for ex: if my file abc.lst contains

     Cable_pull1.sh
       MH_TEST             PAR
       DUAL_DOMAIN         yes
       CAMARO_STORAGE      YES
    
     Flagship.sh
        MH_TEST            NOR
        10_Flags           yes


      Domain_Distibute.sh
        MH_TEST            NOR
        fast_path          YES
        heavy_IO           YES

the requested data needed to extract from above file abc.lst file is below, if file name passed is "Cable_pull1.sh"

   DUAL_DOMAIN         yes
   CAMARO_STORAGE      YES 

if file name is passed "Flagship.sh", expected output is below,

   10_Flags           yes

Below is the code i am trying to get result, where i am kind of lost to extract the required information, please help me with this to extract information i am looking for

    #include<iostream>
    #include<string>
    #include <fstream>
    #include <cstring>
    using namespace std;
    
    bool findWord(string Filename, string const& find)
    {
            cout<<"Filename:"<<Filename<<"\t"<<"find:"<<find<<endl;
            ifstream iFile(Filename.c_str());
            if(!iFile)
            {
                    cerr<<"File not opened!\n";
                    return false;
            }
    
            char c;
            string content;
            while(iFile.get(c) )
            {
                    if(c != '\n')
                    {
                            content += c;
                    }
                    else
                    {
                       content = ""; //reset string after flag ',' was found
                    }
    
                    if(content == find)
                            return true;
            }
            cout<<"content:"<<content<<endl;
            return false;
    }
    
    int main()
    {
       if(!findWord("abc.lst","Cable_pull1.sh"))
          cout<<"failed"<<endl;
        else
         cout<<"success"<<endl;
       return 0;
    }
                                  

Answer 1

I would make use of std::getline to read line by line in the file into a std::string. You can then use the strings member function find to find what you're looking for.

When you've found Cable_pull1.sh for example, you loop, again using std::getline, and print the lines that follows until an empty line is found.

Example:

#include <fstream>
#include <iostream>
#include <string>
#include <vector>

bool findWord(std::string Filename, std::string const& find) {
    std::cout << "Filename:" << Filename << "\tfind:" << find << '\n';
    std::ifstream iFile(Filename.c_str());
    if(!iFile) {
        std::cerr << "File not opened!\n";
        return false;
    }

    std::string line;

    while(std::getline(iFile, line)) {     // read a whole line
        // and find "find" in that line
        std::size_t pos = line.find(find);

        // if "find" is found (pos != std::string::npos),
        // check that it's a full match to the rest of the line
        if(pos != std::string::npos && line.substr(pos) == find) {

            // ok, we found the correct entry in the file
            // loop and print each line (except the "MH_TEST" lines)

            while(std::getline(iFile, line)) {
                if(line.size()==0) break;           // empty line, break out
                if(line.find("MH_TEST") == std::string::npos) {
                    // print lines not matching MH_TEST
                    std::cout << line << '\n';
                }
            }
            return true;
        }
    }
    return false;
}

int main() {
    if(!findWord("abc.lst", "Cable_pull1.sh"))
        std::cout << "failed\n";
    else
        std::cout << "success\n";
    return 0;
}

Output:

Filename:abc.lst        find:Cable_pull1.sh
       DUAL_DOMAIN         yes
       CAMARO_STORAGE      YES
success