I have function:
int read_file() {
ifstream file("plik");
if(!file.is_open()) {
throw -1;
}
int i = 0;
string line[MAXSIZE];
while(getline(plik, line[i])) {
cout<<line[i]<<endl;
i++;
}
return i;
}
But i want to return array of strings:
line[]
How can I do this?
Don't. Arrays are not copyable.
Use a std::vector<std::string> instead.
Standard 8.3.5p6:
Functions shall not have a return type of type array or function, although they may have a return type of type pointer or reference to such things.
As @Tomalak hinted, Just Say No to arrays. They're related to all sorts of gotchas that you can usually avoid if you can use a vector instead.
If you really, really wanted to, you could dynamically allocate an array and return a pointer to that array:
std::string* getArray()
{
return (new std::string[10]);
}
BUT you then need to cater for freeing up the memory you allocated using delete[] to avoid a memory leak.
Ask yourself:
delete[] on it? (Segmentation fault is the answer).std::vector keeps count of the items for you, so no problem there.That's why using an std::vector<std::string> is a better idea. Returning a pointer to a dynamically allocated array introduces all sorts of problems that are better avoided than solved.
vector: How does the calling function know how many elements are in the array?
I'd advise against returning an std::vector<std::string> as well. Instead, I'd pass an iterator, and have the function write the data to wherever the iterator points. This way, the function can equally well write the data to a vector, or a deque, or (if you want) directly to an output stream.
Using that, your function borders on trivial:
// I've changed the definition slightly, to let you pass it a filename instead
// of hard-coding one.
//
template <class outIt>
void read_file(std::string const &filename, outIt output) {
std::ifstream in(filename);
std::string line;
while (std::getline(in, line))
*output++ = line;
}
To use this to copy the data to standard output, roughly as in the question, you'd do something like:
read_file("plik", std::ostream_iterator<std::string>(std::cout, "\n"));
