dynamic string array c++

Question

I created a fixed lenght string:

string fileRows[900];

But sometimes I need more than 900, and sometimes it would be enough 500.

and after that I need to fill the array with a file rows:

...
    string sIn;
    int i = 1;

    ifstream infile;
    infile.open(szFileName);
    infile.seekg(0,ios::beg);

    while ( getline(infile,sIn ) ) // 0. elembe kiterjesztés
    {
        fileRows[i] = sIn;
        i++;
    }

How can i create dynamic lenght for this array?

Use a std::vector<std::string>.

hmjd
– hmjd

2013-03-18 11:14:42 +00:00
Commented Mar 18, 2013 at 11:14 — hmjd
– hmjd, Commented Mar 18, 2013 at 11:14

billz · Accepted Answer · 2013-03-18 11:21:34Z

2

use std::vector, vector is known as dynamic array:

#include <vector>
#include <string>

std::vector<std::string> fileRows(900);

Actually you could just reserve the space for elements and call push_back:

std::vector<std::string> fileRows;
fileRows.reserve(900);   

while (std::getline(infile, sIn))
{
   fileRows.push_back(sIn);
}

edited Mar 18, 2013 at 11:21

answered Mar 18, 2013 at 11:15

billz

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3 Comments

szuniverse Over a year ago

Thanks! It works fine, but if i would like to read the 2. rows how can I do it? fileRows[2] doesnt work.

billz Over a year ago

not before you push_back at least 2 elements. you could always check vector size before call operator[].

szuniverse Over a year ago

Ohh I found it: fileRows.at(1)

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