Fast I/O for competitive programming in Dart by calling getchar() in C.

getchar.dart

import 'dart:ffi' as ffi;

typedef getchar_func = ffi.Int8 Function();
final dylib = ffi.DynamicLibrary.open("/usr/lib/libstdc++.so");
final int Function() getChar =
    dylib.lookup<ffi.NativeFunction<getchar_func>>('getchar').asFunction();

void main() {
	int input = getChar();
	// There's no `char` in Dart. Use the following to convert your ASCII value
	// into a [String]:
	print(String.fromCharCode(input));
}