User Input in the Terminal
Ryan McCombe
So far, our programs have been completely non-interactive. Lets see how we can get input from our users, letting them control how our software runs.
Just like std::cout is a stream of output, std::cin is a stream of input from our user.
There are numerous ways to interact with std::cin. The most straightforward is using std::getline to get a line of text from our users.
There are 3 components to this - first, we need to #include <string> from the standard library:
#include <string>
int main () {}
Then, in one of our functions, we need to create a std::string to store our user input:
#include <string>
int main () {
using namespace std;
string UserInput;
}
Finally, we call std::getline, passing in the std::cin stream, and the string we created to store their input:
#include <iostream>
#include <string>
int main () {
using namespace std;
string UserInput;
cout << "Enter some text: ";
getline(cin, str);
cout << "You entered: " << str;
}
Now, our program will pause at the getline call, and wait for user input. Typing something on our keyboard and hitting return will yield output like the following:
Enter some text: Hello!
You entered: Hello!
Lets see a bigger example of this. The following code lets our user pick what type of Character they want to play as:
#include <iostream>
#include <string>
using namespace std;
class Character {
public:
Character(string ClassName)
: ClassName { ClassName } {
}
void SetName(string NewName) {
Name = NewName;
}
string Name;
string ClassName;
};
class Warrior : public Character {
public:
Warrior() : Character("Warrior") {
}
};
class Rogue : public Character {
public:
Rogue() : Character("Rogue") {
}
};
class Wizard : public Character {
public:
Wizard() : Character("Wizard") {
}
};
string SelectClass() {
cout << "What class do you want to play?" << endl;
cout << "- Enter 1 for Warrior" << endl;
cout << "- Enter 2 for Rogue" << endl;
cout << "- Enter 3 for Wizard" << endl << endl;
cout << "Make your selection: ";
string ClassString;
getline(cin, ClassString);
return ClassString;
}
string SelectName() {
cout << endl << "Enter your name: ";
string Name;
getline(cin, Name);
return Name;
}
int main() {
Character* PlayerCharacter;
Warrior PlayerWarrior;
Rogue PlayerRogue;
Wizard PlayerWizard;
string SelectedClass { SelectClass() };
if (SelectedClass == "1") {
PlayerCharacter = &PlayerWarrior;
} else if (SelectedClass == "2") {
PlayerCharacter = &PlayerRogue;
} else {
PlayerCharacter = &PlayerWizard;
}
PlayerCharacter->SetName(SelectName());
cout << endl
<< PlayerCharacter->Name << " the "
<< PlayerCharacter->ClassName
<< " is entering the arena!";
}
After running this code, and providing the requested input, we might see something like this:
What class do you want to play?
- Enter 1 for Warrior
- Enter 2 for Rogue
- Enter 3 for Wizard
Make your selection: 2
Enter your name: Stabby
Stabby the Rogue is entering the arena!
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Ryan McCombe
Intro to C++ Programming
Become a software engineer with C++. Starting from the basics, we guide you step by step along the way
