write a makefile and compile it

.gitignore

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+bin

Makefile

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+# Makefile for 'Kaiser Operating System (KOS)' (cringe) and my first calculator app
+# This makefile is not part of the original files.
+
+# Compiler
+CXX = g++
+
+# Compiler flags
+CXXFLAGS = -Wall -Wextra -std=c++11 -Ifiles
+
+# Executables
+CALCULATOR = $(BIN)/calculator
+KOS = $(BIN)/kos
+
+# Source files
+CALCULATOR_SRC = files/calculator.cxx
+KOS_SRC = files/KOS.cpp
+
+# Header files
+HEADERS = files/calculator.h files/KOSFunctions.h files/KOSVariables.h
+
+BIN = ./bin
+
+# Default target
+all: $(CALCULATOR) $(KOS)
+
+$(BIN):
+	mkdir -p $(BIN)
+
+# Calculator executable
+$(CALCULATOR): $(CALCULATOR_SRC) $(HEADERS) $(BIN)
+	$(CXX) $(CXXFLAGS) -o $@ $<
+
+# KOS executable
+$(KOS): $(KOS_SRC) $(HEADERS)
+	$(CXX) $(CXXFLAGS) -o $@ $<
+
+# Clean up
+clean:
+	rm -f $(CALCULATOR) $(KOS)
+	rm -rf $(BIN)
+
+.PHONY: all clean