I have some trouble with reading of a file in C++. I am able to read only integers or only alphabets. But I am not able to read both for example, 10af, ff5a. My procedure is as follows:
int main(int argc, char *argv[]) {
if (argc < 2) {
std::cerr << "You should provide a file name." << std::endl;
return -1;
}
std::ifstream input_file(argv[1]);
if (!input_file) {
std::cerr << "I can't read " << ar开发者_开发百科gv[1] << "." << std::endl;
return -1;
}
std::string line;
for (int line_no = 1; std::getline(input_file, line); ++line_no) {
//std::cout << line << std::endl;
-----------
}
return 0;
}
So what I am trying to do is, I am allowing the user to specify the input file he wants to read, and I am using getline to obtain each line. I can use the method of tokens to read only integers or only alphabets. But I am not able to read a mix of both. If my input file is
2 1 89ab
8 2 16ff
What is the best way to read this file?
Thanks a lot in advance for your help!
I'd use a std::stringstream
, and use std::hex
since 89ab and 16ff look like hex numbers.
Should look like this:
std::string line;
for (int line_no = 1; std::getline(input_file, line); ++line_no)
{
std::stringstream ss(line);
int a, b, c;
ss >> a;
ss >> b;
ss >> std::hex >> c;
}
You will need to #include <sstream>
Using
std::string s;
while (input_file >> s) {
//add s to an array or process s
...
}
you can read inputs of type std::string
which could be any combination of digits and alphabets. You don't necessarily need to read input line by line and then try to parse it. >>
operator considers both space and newline as delimiters.
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