Assigning Different Variables to the Input From cin C++

Question

In my lab I'm trying to process a line that represents a destination on Earth. An example of this is ....

"152/N 200/E California Ave"

In my professor's notes, he said that if you did this ...

std::cin >> latitude >> latitudeDirection >> longitude >> longitudeDirection >> address

Which consumes all the way up until California, where from there on out the string is consumed one at a time at each white space. How do I make it so I consume the rest of the input? Here's how my variables look when assigned ...

latitude = 152
latitudeDirection = "/N"
longitude = 200
longitudeDirection = "/E"
address = "California"

address only holds "California" when I want it to hold "California Ave". Here's the code I have so far.

int numberOfLocations;
    std::cin >> numberOfLocations;
    std::cin.ignore();
    for (int x = 0; x < numberOfLocations; x++) {
        double longitude, latitude;
        std::string longitudeDirection, latitudeDirection, address;

        /*
        std::cin >> latitude >> latitudeDirection >> longitude >> longitudeDirection >> address;
        std::cout << latitude << latitudeDirection << latitude << latitudeDirection << address << std::endl;
        */
    }

Check [c++ input with spaces](http://stackoverflow.com/questions/5838711/c-cin-input-with-spaces) — sam, Oct 16 '15 at 00:39

Cheers and hth. - Alf · Answer 1 · 2015-10-16T01:20:47.967

The ordinary >> as input operator splits the input into "words" separated by whitespace.

To avoid that, consider reading one item per line of input. You can use std::getline from <string> to read a line. Where you need a number you can parse the line with e.g. std::stoi.

If you have no choice but to deal with a string that contains multiple items of input, where at the end there's textual data that can contain spaces, then you can use a std::istringstream to read the items before the text.

Example 1 – reading one item per line:

#include <iostream>
#include <stdlib.h>         // exit, EXIT_FAILURE
#include <string>           // std::string
using namespace std;

void error( string const& s )
{
    cerr << "!" << s << endl;
    exit( EXIT_FAILURE );
}

auto get_input_line()
    -> string
{
    string line;
    getline( cin, line );
    if( cin.fail() ) { error( "Uh oh, ..." ); }
    return line;
}

auto main() -> int
{
    cout << "This program adds two numbers A and B." << endl;
    cout << "Number A, please? ";
    double const a = stod( get_input_line() );
    cout << "Number B, please? ";
    double const b = stod( get_input_line() );
    cout << a << " + " << b << " = " << a + b << "." << endl;
}

Example 2 – parsing a line of text
^{(IMHO not smart, but perhaps a requirement)}

#include <iostream>
#include <stdlib.h>         // exit, EXIT_FAILURE
#include <string>           // std::string
#include <sstream>          // std::istrstream
using namespace std;

void error( string const& s )
{
    cerr << "!" << s << endl;
    exit( EXIT_FAILURE );
}

auto main() -> int
{
    string const data   = "152/N 200/E California Ave";

    cout << "This program parses the line '" << data << "'." << endl;
    cout << endl;
    cout << "Result:" << endl;

    istringstream stream( data );
    char    dummy_char;
    int     latitude;
    char    latitudeDirection;
    int     longitude;
    char    longitudeDirection;
    string  address;

    stream
        >> latitude >> dummy_char >> latitudeDirection
        >> longitude >> dummy_char >> longitudeDirection;
    if( stream.fail() ) { error( "Initial items extraction failed." ); }
    while( stream.peek() == ' ' ) { stream.get(); }
    getline( stream, address );

    cout << "> "
        << latitude << "/" << latitudeDirection << " "
        << longitude << "/" << longitudeDirection << " "
        << "'" << address << "'"
        << "<" << endl;
}

would I have to pass the string through a loop to get each value? — Jacob Macallan, Oct 16 '15 at 00:44
From what I'm seeing in the code so far is that you have multiple getlines. The problem is that I have to read one single line of input at a time that includes all of the information I listed above. That's where my problem gets complicated :/ — Jacob Macallan, Oct 16 '15 at 01:00

Pranay Mathur · Answer 2 · 2015-10-16T00:51:28.693

0

The problem here is that, you are trying to enter strings with space, therefore, as inputs via cin are delimited by a space ' ', you will have to use std::getline which will make the end of input delimeter as newline. Example Implementation:

#include <iostream>
using namespace std;
int main()
{
    string s;
    getline(cin,s);
    cout<<s;
    return 0;
}

with this you can enter string with spaces. (end of string will be after a n enter pressed by user, there for end of string delimiter is newline)

edited Oct 16 '15 at 00:51

answered Oct 16 '15 at 00:48

Pranay Mathur

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Unfortunately, I also want to split the string into variable types of doubles and ints as well while at the same time consuming the rest of the string. Is there a convenient way to do that? – Jacob Macallan Oct 16 '15 at 00:50
again there must be some kind of symbols or some other strings on basis of which you have to split the strings, therefore those symbols becomes delimiter for splitting, find the delimeter by find function and and the use substr function. string s = "scott>=tiger"; string delimiter = ">="; string token = s.substr(0, s.find(delimiter)); //output: scott – Pranay Mathur Oct 16 '15 at 00:56
let's say in the above comment s="123>=tiger", then after splitting you will get token="123" then typecast it to integer or float by int x=int(token) – Pranay Mathur Oct 16 '15 at 01:08

Assigning Different Variables to the Input From cin C++

2 Answers2