Read tabs separated file into arrays in c++

Question

I have file like this:

int1--tab--int2--tab--int3--tab--int4--tab--newline

int1--tab--int2--tab--int3--tab--int4--tab--newline ...

I want to save each row in to an array. I mean all int1 in to an array and want to do the same whit int2 int3 ...

I realy dont know how to do it please help me

I already try read it line by line

#include <sstream>
#include <string>

std::string line;
while (std::getline(infile, line))
{
    std::istringstream iss(line);
    int a, b;
    if (!(iss >> a >> b)) { break; } 

}

Not a bad attempt. Do you know there are always 4 columns? Do you know about vector<int> ? — Captain Giraffe
– Captain Giraffe, Commented Nov 14, 2013 at 22:27
is the "--" in your file a separator you added to make it clear, or are there really "--" in the file? — Paweł Stawarz
– Paweł Stawarz, Commented Nov 14, 2013 at 22:31

benjamin · Accepted Answer · 2013-11-14 22:43:32Z

You had the right idea using a stringstream. Since code to read delimited files is likely to be used again, you may find it useful to put this into class. Here's an excerpt from my personal delimited FileReader class:

bool FileReader::getrow(RowMap &row){
    std::string line = "";
    if(std::getline(filehandle,line)){
        std::stringstream line_ss(line);
        std::string column = "";
        unsigned int index = 0;
        while(std::getline(line_ss,column,delimiter)){
            if(index < headers.size()){
                row[headers[index]] = column;
                index++;
            }
            else{
                break;
            }
        }
        return true;
    }
    return false;
}

Where RowMap is a typedef of:

typedef std::unordered_map<std::string,std::string>

And headers is a typedef of:

typedef std::vector<std::string> RowHeadersVector;

And should have your column names:

RowHeadersVector headers;
headers.push_back("column_1");

In my example, I'm using a map of string to string, but you could easily change it to:

typedef std::unordered_map<std::string,int>

The benefit of using a map like this is self documented code:

row["column_1"]

Dietmar Kühl · Accepted Answer · 2013-11-14 22:46:23Z

1

This looks quite reasonable. If you know the number of columns, you can just create suitable arrays and add them:

std::vector<int> array, barray, carray, darray;
std::istringstream lin;
for (std::string line; std::getline(infile, line); ) {
    lin.clear();
    lin.str(line);
    if (lin >> a >> b >> c >> d) {
        aarray.push_back(a);
        barray.push_back(b);
        carray.push_back(c);
        darray.push_back(d);
    }
    else {
        std::cout << "WARNING: failed to decode line '" << line << "'\n";
    }
}

answered Nov 14, 2013 at 22:46

Dietmar Kühl

155k18 gold badges238 silver badges395 bronze badges

Comments

john · Accepted Answer · 2013-11-14 22:43:51Z

0

It's strange that you've done the hard part and are stuck on what seems to me to be the easy part.

Just replace a and b with arrays and an index.

int a[100], b[100];
int count = 0;
std::string line;
while (std::getline(infile, line))
{
    std::istringstream iss(line);
    if (!(iss >> a[count] >> b[count])) { break; } 
    ++count;
}

At the end of this loop count will tell you how many items you've added to the arrays. Of course this code will crash if you try to add more than 100 items to the arrays. I'll leave you to think about that.

answered Nov 14, 2013 at 22:43

john

88.3k5 gold badges61 silver badges95 bronze badges

1 Comment

marek094 Over a year ago

What if a whitespace appears in a column?

Collectives™ on Stack Overflow

Read tabs separated file into arrays in c++

3 Answers 3

Comments

Comments

1 Comment

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Linked

Related