Splitting a string into multiple primitive types

Question

I'm writing a program that reads a string from the user and uses it to process a request. After issuing a prompt, I can expect one of three possible responses in the form of either:

string string
string integer
string

Depending on which type of command the user gives, the program is to do a different task. I'm having a difficult time trying to process the users input. To be clear, the user will type the command as a single string, so an example of a user exercising option two might input "age 8" after the prompt. In this example I would like the program to store "age" as a string and '8' as an integer. What would be a good way of going about this?

From what I've gathered on here, using strtok() or boost might be a solution. I've tried both without success however and it would be very helpful if someone could help make things clearer. Thanks in advance

something like `string str; int num; cin >> str >> num;` doesn't work for you? — Shahbaz, Apr 17 '12 at 15:18
I suppose the only problem would be how to determine if the user gave input in the form of string string, or string, instead of string integer as in the example. — Jaimie Knox, Apr 17 '12 at 15:25
@Shahbaz: That won't work in case 3. You'd want to read a line, then parse that, perhaps from a `stringstream`. — Mike Seymour, Apr 17 '12 at 15:25
@MikeSeymour, sorry I understood that the user first gives his choice, then enters one of the three forms. — Shahbaz, Apr 17 '12 at 16:07

score 6 · Accepted Answer · answered Apr 17 '12 at 15:26

After getting one line of input with std::getline, you can use a std::istringstream to recycle the text for further processing.

// get exactly one line of input
std::string input_line;
getline( std::cin, input_line );

// go back and see what input was
std::istringstream parse_input( input_line );

std::string op_token;
parse_input >> op_token;

if ( op_token == "age" ) {
    // conditionally extract and handle the individual pieces
    int age;
    parse_input >> age;
}

@JaimieKnox Welcome to SO! If this solved your problem, click the green check mark at top left beside this answer. — Potatoswatter, Apr 17 '12 at 15:35

Splitting a string into multiple primitive types

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