Because your 'while' loop is incorrect. 'eof()' does not report true until *after* an attempt to read past end of file. It does not 'predict' the next read will fail.

>
> Could someone give me a clue to modify my program such that it can
> display "data.txt" properly under Windows and Linux?

#include #include #include #include #include

int main() { int ret(EXIT_SUCCESS); std::ifstream fp_input("data.txt");

if(fp_input) { std::string line;

while(std::getline(fp_input, line)) { std::istringstream iss(line); int a(0);

if(iss >> a) { std::cout << a << ": "; int b(0);

while(iss >> b) std::cout << b << ", ";

if(!iss.eof()) { std::cerr << "Error reading input\n"; ret = EXIT_FAILURE; break; }

std::cout << '\n'; } else { std::cerr << "Error reading input\n"; ret = EXIT_FAILURE; break; }

} } else { std::cerr << "Cannot open input\n"; ret = EXIT_FAILURE; }

return ret; }

Note that if the last line of the input file is empty (contains only a newline character), parsing it will cause an error to be reported, since your algorithm unconditionally expects an integer as the first part of a line (the item you read into object 'a'). You'll either need to eliminate this 'requirement', or remove the blank line.

-Mike