Merge pull request #14 from DoctorLai/map-with-unknown-key

Map with unknown key

Author: doctorlai-msrc

.github/workflows/ci.yml

@@ -20,7 +20,7 @@ jobs:
       - name: Install build tools
         run: |
           sudo apt-get update
-          sudo apt-get install -y build-essential g++ clang clang-format
+          sudo apt-get install -y build-essential g++-14 clang clang-format
 
       # 3. Clang-format check
       - name: Clang-format Check

README.md

@@ -30,6 +30,8 @@ Examples include (and will expand to):
     * [integer-factorization](./integer-factorization/)
     * Encoding
         * [rot47](./rot47/)
+* Data Structures
+    * [map-with-unknown-key](./map-with-unknown-key/)
 * OOP
     * [virtual-interface](./virtual-interface/)
     * [oop-with-exception](./oop-with-exception/)
@@ -63,6 +65,12 @@ cpp-coding-exercise/
 
 ## Building
 
+### C++ Version
+```bash
+sudo apt update
+sudo apt install g++-14
+```
+
 ### Build everything
 
 ```bash

common.mk

@@ -26,6 +26,7 @@ endif
 # --------------------------
 # Compiler / Linker flags
 # --------------------------
+CXX := g++-14
 CXXFLAGS := -std=c++23 -Wall -Wextra -Werror $(OPTFLAGS) $(SAN_FLAGS)
 LDFLAGS  := $(SAN_FLAGS)
 

map-with-unknown-key/Makefile

@@ -0,0 +1,31 @@
+# pull in shared compiler settings
+include ../common.mk
+
+# per-example flags
+# CXXFLAGS += -pthread
+
+## get it from the folder name
+TARGET := $(notdir $(CURDIR))
+## all *.cpp files in this folder
+SRCS   := $(wildcard *.cpp)
+OBJS   := $(SRCS:.cpp=.o)
+
+all: $(TARGET)
+
+$(TARGET): $(OBJS)
+	$(CXX) $(CXXFLAGS) -o $@ $^
+
+%.o: %.cpp
+	$(CXX) $(CXXFLAGS) -c $< -o $@
+
+run: $(TARGET)
+	./$(TARGET) $(ARGS)
+
+clean:
+	rm -f $(OBJS) $(TARGET)
+
+# Delegates to top-level Makefile
+check-format:
+	$(MAKE) -f ../Makefile check-format DIR=$(CURDIR)
+
+.PHONY: all clean run check-format

map-with-unknown-key/main.cpp

@@ -0,0 +1,19 @@
+/**
+What happens if you access an unknown key in the std::map, std::unordered_map?
+*/
+#include <iostream>
+#include <map>
+#include <string>
+#include <format>
+#include <print>
+
+int
+main()
+{
+    std::map<std::string, int> my_map;
+    std::print("Accessing unknown key 'unknown_key' in std::map:\n");
+    int value = my_map["unknown_key"];
+    std::print("Value: {}\n", value);                         // Should print 0, as default-constructed int is 0
+    std::print("Map size after access: {}\n", my_map.size()); // Should print 1
+    return 0;
+}

map-with-unknown-key/tests.sh

@@ -0,0 +1,5 @@
+#!/bin/bash
+
+set -ex
+
+./map-with-unknown-key