Is there a way I can write a string into a FILE? - c++

Question

I'm trying to write a string into a file, but I don't know how to do it, I have tried to use wstring instead of string in my randomString() string function, and other things just to write a string to a file.
The if condition is checking if file is created, and if yes, write to it.
fopen is used to open the file, path1 variable is the path to my file, and the "w" is equal to write.
randomString() is a string function.
char buffer[100] = { randomString() };
FILE* file;
file = fopen(path1, "w");
if (file) {
fwrite(buffer, sizeof(char), sizeof(buffer), file);
fclose(file);
}
return;

Answer 1

If you're using a new-ish compiler you can try std::filesystem
#include <iostream>
#include <fstream>
#include <filesystem>
namespace fs = std::filesystem;
int main() {
auto directoryToWriteTo = fs::current_path(); // returns a fs::path object
std::ofstream fileStream(directoryToWriteTo.string() + "/nameOfYourFile.txt");
if(fileStream.is_open())
fileStream << "Whatever string you want to write to a file\n";
}
std::filesystem isn't needed for writing to one file, but it does make things like iterating over all files in a directory easy, as adapted from the cppreference.com examples.
#include <fstream>
#include <iostream>
#include <filesystem>
namespace fs = std::filesystem;
int main() {
auto directoryToTraverse = fs::current_path();
for(auto& p: fs::directory_iterator(directoryToTraverse)){
if(fs::is_regular_file(p)){
std::ofstream tmpStream(p,std::ios_base::app); //open file in append mode
tmpStream << "Append a string to each regular file in your directory\n";
}
}
}
It also allows one to change file permissions programmatically with standard c++.

Answer 2

If you are just trying to print out to a file the contents of a string, using fwrite, then you need to do something like the following
std::string str = randomString();
if ( file ) {
fwrite( str.c_str(), sizeof( char ), str.size(), file );
fclose( file );
}
Since fwrite expects the first parameter to be void *, an std::string is not compatible; however, a char * is. By calling .c_str() on the string, you would have a char * to work with. The second parameter is the size of the type, which for a std::string is char, so sizeof( char ) gives the size (which is 1). The third parameter is the count (number of characters to write), which can easily be gotten from str.size().