I/O Redirection

Many programs take input from the console (stdin) and print output to the console (stdout and stderr). For example, consider this simple program that asks the user for a name and then greets the user:
hello.cpp
```
#include <iostream>
using namespace std;

int main() {
    cout << "Name: ";
    string name;
    getline(cin, name);
    cout << "Hello, " << name << "!" << endl;
}
```
In Terminal, we can compile and run this program with
```
./hello
```
We would have to type input ourselves and we would see the output in the console:
```
Name: Maxim
Hello, Maxim!
```
However, we sometimes want our program to read input from a file instead of the console. In Terminal, we would execute something like this to use the contents of input.txt as input:
```
./hello < input.txt
```
Similarly, we can redirect output of the program so some file, such as output.txt:
```
./hello > output.txt
```
After executing this command, output.txt will contain the output of the program. This file will be overwritten if it already exists or created if it does not exist.
We can also combine input and output redirection in Terminal with
```
./hello < input.txt > output.txt
```

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