I was having an issue when I ran a program in Xcode Debugger Console that utilized scanf() the program would just hang.
The program would work correctly when run directly from the Terminal.
The only solutions that I could find online were to install a previous version of Xcode.
When entering standard input, you need to terminate your string with the forward slash ‘/’.
4556/ <—- This is what you input
Sum of 4556 = 21