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I'm trying to make a function that writes a file but i'm having issues passing a string as a parameter. 

void writeFile(string filename, string letters, int size)
{
     ofstream outputfile("output.txt");
     outputfile << letters;
     outputfile.close();

 }

int main()
{
    string letters[] = {"u", "l", "s", "n","m", "z", "a", "p", "b"};

    int size = 9;

    string filename = "Inputfile.txt";

    writeFile(inputfilename.c_str(),letters,size);

}

And having this error. 

error: could not convert from 'std::string* {aka std::basic_string<char>*}' to 'std::string {aka std::basic_string<char>}'|
SaltyCode
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  • What's `unsortedValues`? – songyuanyao Oct 28 '16 at 02:48
  • Where is the variable `unsortedValues`? The error indicates that it's a `string*` instead of `string`. – Barmar Oct 28 '16 at 02:48
  • Should that be `letters` instead of `unsortedValues`? – Barmar Oct 28 '16 at 02:49
  • Why are you using `inputfilename.c_str()` when the `filename` argument is supposed to be a `std::string`, not a C string? – Barmar Oct 28 '16 at 02:49
  • letter is an array of string, your writeFile() function takes a string in the second parameter. – KC Wong Oct 28 '16 at 02:49
  • UnsortedValues was meant to be a string that is supposed to be sorted. To simplify the code and issue i shortened it down a bit. – SaltyCode Oct 28 '16 at 02:50
  • We won't magically know what unsortedValues is. What if your error is in the way you sort letters into unsortedValues? – KC Wong Oct 28 '16 at 02:51
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    @SaltyCode `writeFile()` just wants one string to write to the file, but you're giving it an array. The error message is very clear about that. – Barmar Oct 28 '16 at 02:52
  • @KC Wong yeah sorry about that. But as you suggested i changed the parameter to expect an array as `string words[]`. – SaltyCode Oct 28 '16 at 03:01

2 Answers2

3

An array of string items is passed as actual argument, where the formal argument is a single string.

You could replace the array with a single string.

Or with a set, or whatever suits the purpose, but then you'll have to change the called function accordingly.

The error mentions std::string* instead of an array, like std::string[9], because the array expression decays to an expression denoting a pointer to the first item, which it does because the array is not being bound to a reference or passed to sizeof or anything where the expression's array nature would have to be preserved.

Cheers and hth. - Alf
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The problem was that

void writeFile(string filename, string letters, int size)

is expecting a string but,

string letters[] = {"u", "l", "s", "n","m", "z", "a", "p", "b"};

is an array of string, i "fixed" it by changing the function second parameter to

void writeFile(string outputFileName, string words[], int arraylength)

with "fixed" i meant that regardless of that now it does creates a file named "output.txt" but the content is not the array of string passed as a second parameter.

SaltyCode
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