Question

The output is an infinite loop of “cannot open the file”. what did I do wrong? thanks in advance. (p.s I am trying to test the condition that it cannot open the file and continue processing by getting the next file name from the vector)

#include <iostream>
#include <istream>
#include <fstream>
#include <vector>
#include <string>
using namespace std;
int main ()
{
ifstream input;
vector<string> files;
files.push_back("ifile");
files.push_back("ifile2");
vector<string>::const_iterator iter=files.begin();
while (iter!=files.end())
{   
    string s;
    input.open(iter->c_str());
    if (!input)
    {
        cerr<<"cannot open the file"<<endl;
        input.close();
        input.clear();
        continue;
    }
    while(input>>s)
        cout<<s<<' '<<ends;
    input.close();
    input.clear();
    cout<<endl;
    ++iter;
}
return 0;
}

Answer 1

Simply enough, you’re not incrementing the iterator in your error case.