I'm trying to pass variable number of ofstreams over to a function that accepts an initializer_list but doesn't seem to work and throws all possible errors from the initializer_list structure and about how my function is with an array of ofstreams cannot be matched to any defined function.
Is it actually possible to pass a reference of ofstreams over in an initializer_list?
test.cpp
#include "extension.h"
ofstream outputFile, outputFile2;
int main(void) {
outputFile.open(("data_1.txt");
outputFile2.open("data_2.txt");
writeSomething({outputFile, outputFile2});
outputFile.close();
outputFile2.close();
}
extension.h
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <iostream>
#include <fstream>
#include <unistd.h>
#include <string.h>
#include <initializer_list>
using namespace std;
void writeSomething(initializer_list<ofstream&> args);
extension.cpp
#include "extension.h"
void writeSomething(initializer_list<ofstream&> args) {
for (auto f : args ) {
f << "hello" << endl;
}
}
clang 3.4 (trunk 194324) produces a pretty clear error message:
initializer_list:54:23: error: 'iterator' declared as a pointer to a reference of type
'std::basic_ofstream<char> &'
typedef const _E* iterator;
So no, it is not possible. See also Error: forming pointer to reference type 'const std::pair&'… I can't understand this error.
(gcc 4.7.2 and 4.8.1 crashes on this code due to some internal compiler error. I have submitted a bugreport.)
What you could do instead is to pass a pointer instead of a reference, something like this:
#include <fstream>
#include <initializer_list>
using namespace std;
void writeSomething(initializer_list<ofstream*> args) {
for (auto f : args )
*f << "hello" << endl;
}
int main() {
ofstream outputFile("data_1.txt");
ofstream outputFile2("data_2.txt");
writeSomething({&outputFile, &outputFile2});
}
However, I would much rather use a std::vector
instead. Using an initializer list for this purpose is very strange and confusing for me.