Question

I am a new learner to C++.
I have a text file, its contents like following:

Systemname    localtesthost
SystemIp      X.X.X.X
Systemowner   root
...

Now I want to extract the value of “Systemname”, that is “localtesthost”.

And I can extract the line containing “Systemname localtesthost”, but I don’t know how to extract the String “Systemname”.

Below is my program need help:

const char* configInfoFile = "config_info";//the text file name
ifstream ifs(configInfoFile);
    string line;
    while(getline(ifs,line)) {
        if(line.length() > 0){
            int index = line.find("SystemName");
            if (index != -1)
            {

                                .
                                .

            }

        } 
}

Could any one show me how to extract the string "localtesthost"?

Many thanks!

Answer 1

Here is an approach:

1. create a std::istringstream using the line you just read in.
2. read from the stream two std::string objects, key and value
3. if the key matches what you are looking for, value should contain what you require.