Cannot push back a string into a vector of strings c++ - c++

Question

I'm trying to create a program to separate a single line into a vector of strings separated by the blank spaces in said line, so turn:
foo bar
into
["foo", "bar"]
This is what I have so far:
string command;
string command_temp;
vector<string> command_seperated;
std::cin >> command;
for (int i = 0; i < command.length(); i++){
if (isspace(command[i])){
cout << "blankspace" << endl; command_seperated.push_back(command_temp);
command_temp.clear();
}
command_temp.push_back(command[i]);
for (int i = 0; i < command_temp.size(); i++){
cout << command_temp[i];
}
cout << endl;
}
for (int i = 0; i < command_seperated.size(); i++){
cout << command_seperated[i] << endl;
}
But, if I input "foo bar" when prompted, this just returns:
foo bar
f
fo
foo
Process returned 0 (0x0) execution time : 2.596 s
Press any key to continue
I assume the reason the last for loop isn't printing anything is that there's nothing in it and the push_back to command_seperated isn't working. I have no idea why.
I also don't know why the entire program seems to just stop working after the first blank space.
Using this to refresh my rudimentary C++ skills, so I would appreciate an explanation of why I'm wrong, rather than a more elegant alternative solution.

Answer 1

What you are seeing is normal behavior of operator>>, which is used for reading formatted input. It skips leading whitespace (if the skipws flag is enabled on the stream, which it normally is), then reads until EOF or whitespace is encountered. So, in your example, std::cin >> command receives only foo even though you entered foo bar. If you invoked std::cin >> command a 2nd time, you would receive bar.
To read a string that contains whitespace in it, use std::getline() instead:
std::getline(std::cin, command);
It does not skip leading whitespace, and reads until EOF or a linebreak (ie, from typing Enter) is encountered.
That being said, the parsing code you have shown can be greatly simplified if you use a std::istringstream with operator>> to parse the command, eg:
std::string command, token;
std::vector<std::string> command_seperated;
std::getline(std::cin, command);
std::istringstream iss(command);
while (iss >> token) {
command_seperated.push_back(token);
}
for (const auto &str : command_seperated){
cout << str << endl;
}