错误：无法从&#39;std :: string * {aka std :: basic_string转换 <char> *}&#39;为&#39;std :: string {aka std :: basic_string <char> }&#39;|

Question

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>}'|

Answer 1

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.

Answer 2

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.