C++ restore/pass a vector (what to call in the header?)

Question

I am learning C++ at school and I am adding some functions to my school project. We need to code a program, which searches a word in files in folders.

I am at the point, where I want to list all directories and files and pass them back (with return), so I can display (output) them at the console.

So I used a vector type string and pushed back all the paths I found... Then I wanted to give (pass) them back with return, but I got the Error:

error: cannot convert `std::vector<std::string, std::allocator<std::string> >' to `std::string*' in return

Here is some Code:

string OpenFolder(string path, const string constSearchedWord)


vector<string> vIndex;         //Vektor erzeugen
vector<string>::iterator i;    //Iterator (zum durchlaufen)

...

while ( 0 != ( dirEntry = readdir( dirHandle ) ) )
    {
        string name = dirEntry->d_name;
        fullPath = path + '\\' + name;
        vIndex.push_back(fullPath);
    }
    //Den Ordner schliessen
    closedir( dirHandle );

... If I wanted to write it into the console in this function:

for (i = vIndex.begin(); i < vIndex.end(); ++i)
{
    cout << static_cast<string>(*i) << endl;
}

is working easily, but I don't want to write it in this function into the console.

I want to do

return vIndex;

I think the problem is in the header:

string OpenFolder(string path, const string constSearchedWord)

I tried

vector OpenFolder(string path, const string constSearchedWord)

But this didn't work either.

I don't know what to set here:

->???<- OpenFolder(string path, const string constSearchedWord)

You are most definitely not learning C. C has no `std::vector`. — The Paramagnetic Croissant, Jan 21 '15 at 20:49
BTW, if the variable you're returning is a `vector`, then isn't it kind of obvious that the return value also needs to be a `vector`? — The Paramagnetic Croissant, Jan 21 '15 at 20:52
@The Paramagnetic Croissant well, of course. I dont know, how I could forgot this...But thanks — Sinmson, Jan 21 '15 at 20:54

score 1 · Accepted Answer · answered Jan 21 '15 at 20:48

1

Change the return type of function OpenFolder

string OpenFolder(string path, const string constSearchedWord)
~~~~~ should be std::vector < std::string >

Also,

use const reference for function arguments

std::vector<std::string> OpenFolder(const string& path,
                                    const string& constSearchedWord )

answered Jan 21 '15 at 20:48

P0W

46,614
9
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sorry, but why the `string&`, where is the differents to `string` ? – Sinmson Jan 21 '15 at 20:52
@Sinmson That's a reference. Google "C++ reference" if you don't recognize the term. – The Paramagnetic Croissant Jan 21 '15 at 20:54
@The Paramagnetic Croissant ok, thanks. I searched it and know why this is better in the theory. But is there a differens in the praxis, for real? – Sinmson Jan 21 '15 at 20:58
@Sinmson Sometimes there is, sometimes there isn't. But does it matter? I doubt. When this becomes a *measurable* bottleneck, only then think about it. – The Paramagnetic Croissant Jan 21 '15 at 21:34

score 0 · Answer 2 · answered Jan 21 '15 at 20:51

0

if you want to return the vector of strings from a method then the return type needs to be a vector of strings i.e.

std::vector<std::string> OpenFolder(string path, const string constSearchedWord)

answered Jan 21 '15 at 20:51

Paul

94
1
9

score 0 · Answer 3 · answered Jan 21 '15 at 20:56

0

A function definition/declaration generally takes the form of ...

[return type] [function name]([arguments])

If you're returning vIndex from the OpenFolder function then the return type needs to match the type of vIndex, which is vector<string>.

answered Jan 21 '15 at 20:56

gmbeard

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C++ restore/pass a vector (what to call in the header?)

3 Answers3