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cplusplus/geminitutorial/tutorial2/tutorial-2.2-plan.md

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+# Tutorial 2.2 Plan: Modern STL Containers & Algorithms
+
+**Objective:** Use the workhorse containers and algorithms with a focus on performance. The project involves parsing mock CSV tick data using algorithms and lambdas to perform queries.
+
+---
+
+## 1. Project Setup
+
+We will continue working within the `tutorial-2` directory. No new directory creation is needed.
+
+## 2. Defining Tick Data Structure
+
+We'll define a simple struct to represent a tick, containing a timestamp, price, and volume.
+
+**File:** `tutorial-2/src/TickData.h`
+```cpp
+#pragma once
+
+#include <string>
+#include <chrono>
+
+struct TickData {
+    std::chrono::system_clock::time_point timestamp;
+    double price;
+    long volume;
+
+    // Optional: for easy printing/debugging
+    std::string toString() const;
+};
+```
+
+## 3. CSV Parsing Utility
+
+We'll implement a function to parse a single line of CSV data into a `TickData` object. This will involve string manipulation and conversion. `std::string_view` will be crucial here for zero-copy parsing.
+
+**File:** `tutorial-2/src/CsvParser.h`
+```cpp
+#pragma once
+
+#include "TickData.h"
+#include <string>
+#include <vector>
+
+namespace CsvParser {
+    TickData parseTickCsvLine(std::string_view line);
+    std::vector<TickData> parseTickCsvFile(std::string_view filename);
+} // namespace CsvParser
+```
+
+**File:** `tutorial-2/src/CsvParser.cpp`
+```cpp
+#include "CsvParser.h"
+#include <fstream>
+#include <sstream>
+#include <stdexcept>
+#include <iostream> // For error reporting
+
+// Implement parseTickCsvLine and parseTickCsvFile
+```
+
+## 4. Main Application: Parsing and Querying
+
+In `tutorial-2/src/main.cpp`, we will:
+1. Generate some mock CSV tick data (or read from a static file).
+2. Use `CsvParser::parseTickCsvFile` to load the data into a `std::vector<TickData>`.
+3. Perform various queries using modern STL algorithms and lambdas:
+    *   Find the highest price.
+    *   Calculate the total volume.
+    *   Filter ticks above a certain price.
+    *   Find the average price within a time range.
+    *   Use `std::unordered_map` to aggregate volume by some key (e.g., minute of the hour).
+
+## 5. Updating the Build System
+
+Modify `tutorial-2/CMakeLists.txt` to include `TickData.cpp` and `CsvParser.cpp` (if needed, `TickData` might just be a header). Ensure proper linking.
+
+## 6. Summary and Key Takeaways
+
+This tutorial will provide hands-on experience with:
+*   Efficient string handling using `std::string_view`.
+*   Storing structured data in `std::vector`.
+*   Performing data transformations and queries using STL algorithms and lambdas.
+*   Using `std::unordered_map` for fast lookups and aggregations.