CODEWITHSUNDEEP
c++stringtypesintidentify
Nicklas Bo Nielsen
Nicklas Bo Nielsen

Reputation: 1

How to identify data type from file

So I need to know how to identify a line of text and output what kind of data type it is, like if the line says 123, it should be output as 123 int.

Right now, my program only identifies boolean, string, and char. How do I get it to tell me if it is an int or a double?

int main() {
    string line;
    string arr[30];
    ifstream file("pp.txt");
    if (file.is_open()){
        for (int i = 0; i <= 4; i++) {
            file >> arr[i];
            cout << arr[i];
            if (arr[i] == "true" || arr[i] == "false") {
                cout << " boolean" << endl;

            }
            if (arr[i].length() == 1) {
                cout << " character" << endl;

            }
            if (arr[i].length() > 1 && arr[i] != "true" && arr[i] != "false") {
                cout << " string" << endl;
            }
        }
        file.close();
    }
    else
        cout << "Unable to open file";
    system("pause");
}

Thanks

Upvotes: 0

Views: 1222

Answers (1)

user6238175
user6238175

Reputation:

Use regex: http://www.cplusplus.com/reference/regex/

#include <regex>
std::string token = "true";
std::regex boolean_expr = std::regex("^false|true$");
std::regex float_expr = std::regex("^\d+\.\d+$");
std::regex integer_expr = std::regex("^\d+$");
...
if (std::regex_match(token, boolean_expr)) {
    // matched a boolean, do something
}
else if (std::regex_match(token, float_expr)) {
    // matched a float
}
else if (std::regex_match(token, integer_expr)) {
    // matched an integer
}
...

Upvotes: 1

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