empidocl empidocl - 1 year ago 95
C++ Question

open file, save duplicate with different name

Hello c++ newbie over here !!!

I am working on a very simple program, that opens files saved into a vector, reverses the content text for each files, and saves the new file.
I am using code blocks


  • open "test.txt"

  • reverse lines

  • creates "m_test.txt"

  • delete "test.txt"

  • do the same to other files in the vector.

I get an error in :
outFile.open( foundFiles[i].insert(3,"m_"), fstream::in);

" no matching function for call to 'std::basic_fstream::open(std::basic_string&, std::_Ios_Openmode)'| "

here is the code so far:

 string reverseLine(string message);

string reverseLine(string message)
string reversed;
int i = message.length() -1;
while (i>=0)
reversed = reversed + message[i];
i = i -1;
return reversed;

void filesToModify();

void filesToModify() // put files into vector

fstream filesInVector; // files open from the vector
string openFLine; // lines read from the files read from the vector

fstream outFile; //files saved after reversing the files

vector <string> foundFiles; //vector holding all the files to be reversed


for (int i=0; i<foundFiles.size(); i++) // read the files inside the vector
filesInVector.open(foundFiles[i], fstream::in);

while (!filesInVector.eof())
outFile.open( foundFiles[i].insert(3,"m_"), fstream::in); // add "m_" to the created file
foundFiles[i].close(); // close the file

std::remove(foundFiles[i]); // remove the original file

int main()



Answer Source
outFile.open( foundFiles[i].insert(3,"m_").c_str (),  fstream::in);

C++ used to have no string datatype. It was added later in the STL (standard template library. These early C++ versions used a char* (pointer to character). A string was simply represented by a character array, terminated by a 0 char (char with code 0). The pointer held the address of the first char of this array.

Some functions still expect a char* instead of a string. Method c_str () of STL class string converts an STL string to a char*.

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