ifstream，Getline返回一个内存地址

Question

i have the following code:

std::ifstream report( fileToRead );
cout << "leyendo archivo: " << fileToRead << endl;
std::string line;
cout << std::getline(report,line) << endl;
report.close();

But cout give the following result: 0x28fe64 What can I do?

Answer 1

Base on this reference, http://www.cplusplus.com/reference/string/string/getline/ .

The getline function return reference to an ifstream object, that is the reason you get an address printed.

You need cout << line; to print out the content read.

I also failed to repeat your bug, which version of g++ and OS you are using? My g++ as following:

Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/usr/include/c++/4.2.1 Apple LLVM version 6.1.0 (clang-602.0.53) (based on LLVM 3.6.0svn) Target: x86_64-apple-darwin14.3.0 Thread model: posix

#include <fstream>
#include <iostream>
using namespace std;

int main(int argc, char * argv[]){
    char * fileToRead= "a.txt";
    std::ifstream report( fileToRead );
    cout << report << endl;

    cout << "leyendo archivo: " << fileToRead << endl;
    std::string line;
    cout << std::getline(report,line) << endl;
    cout << std::getline(report,line) << endl;
    cout << std::getline(report,line) << endl;
    cout << std::getline(report,line) << endl;
    cout << std::getline(report,line) << endl;
    cout << std::getline(report,line) << endl;
    report.close();
}

The result I got is:

1
leyendo archivo: a.txt
1
1
1
0
0
0

It seems that the ifstream is converted to boolean variable indicating whether there are any file operation error with the ifstream. The final three zero is due to there is no more lines to read.