CODEWITHSUNDEEP
c++string
skazhy
skazhy

Reputation: 4651

How to parse a date encoded as DD.MM.YYYY and extract the parts to ints

I have the following data in a c++ string

John Doe 01.01.1970

I need to extract the date and time from it into int variables. I tried it like this:

int last_space = text_string.find_last_of(' ');
int day = int(text_string.substr(last_space + 1, 2));

But I got invalid cast from type ‘std::basic_string’ to type ‘int’. When I extract the "John Doe" part in another string variable, all works fine. What's wrong?

I am trying to compile it with g++ -Wall -Werror.

Upvotes: 5

Views: 20108

Answers (5)

Loki Astari
Loki Astari

Reputation: 264331

Use streams to decode integers from a string:

#include <iostream>
#include <sstream>
#include <string>

int main()
{
    std::string         x = "John Doe 02.01.1970";

    std::string         fname;
    std::string         lname;
    int                 day;
    int                 month;
    int                 year;
    char                sep;

    std::stringstream   data(x);
    data >> fname >> lname >> day >> sep >> month >> sep >> year;

    std::cout << "Day(" << day << ") Month(" << month << ") Year(" << year << ")\n";
}

The operator >> when used with a string variable will read a single (white) space separate word. When used with an integer variable will read an integer from the stream (discarding any proceeding (white) space).

Upvotes: 3

Mark
Mark

Reputation: 10162

Assuming (and that might be a bad assumption) that all the data was formatted similarly, I would do something like this

char name[_MAX_NAME_LENTGH], last[_MAX_NAME_LENGTH];
int month, day, year;

sscanf( text_string, "%s %s %2d.%02d.%04d", first, last, &month, &day, &year );

This does however, have the problem that the first/last names that appear in your input are only one word (i.e. this wouldn't work for things like "John M. Doe"). You would also need to define some appropriate maximum length for the string.

It's hard to be more definitive about this solution unless we know more about the input.

Upvotes: 0

Axel Gneiting
Axel Gneiting

Reputation: 5393

You need to use 

std::stringstream ss; 
ss << stringVar;
ss >> intVar;

or

intVar = boost::lexical_cast<int>(stringVar);.

The later is a convenience wrapper from the boost library.

Upvotes: 5

Maxpm
Maxpm

Reputation: 25551

As far as I can tell, atoi does what you need.

"Parses the C string str interpreting its content as an integral number, which is returned as an int value."

http://www.cplusplus.com/reference/clibrary/cstdlib/atoi/

Upvotes: 0

yasouser
yasouser

Reputation: 5177

Try the Boost Data/Time library.

Upvotes: 2

Related Questions