讀書心得 - C++ Primer (5th Edition) - Chapter 1

簡單的 C++ 程式

    要寫一個 C++ 程式跟 C 一樣，寫好 cpp 檔，交給編譯器 ( g++ ) 編成可執行程式。程式至少包含一個名為 main 的 function，用以當作程式的入口 function。

    int main() {
        return 0; // return 0 的原因為 0 通常代表著程式執行成功。
    }

Input/Output

    C++ 本身並沒有定義 I/O，需要額外的標準函式庫，iostream。

    #include <iostream>
    int main()
    {
        // operator << >> 會回傳左邊的 operand
        // 以 std::cin >> v1 >> v2; 為例
        // 執行結果 =
        //     std::cin >> v1;
        //     std::cin >> v2;
        int v1, v2;
        std::cout << "Enter two numbers:" << std::endl;
        std::cin >> v1 >> v2;
        std::cout << "The sum of " << v1 << " and " << v2 << " is " << v1 + v2 << std::endl;
        return 0;
    }

Note

• std::endl : std::endl vs "\n"

常用詞彙

• prompt 提示 驅使
  
  We can extend our main program to prompt the user to give us two numbers and then print their sum
  
  
• expression （數學中的）式，表達式
  
  The smallest unit of computation. An expression consists of one or more operands and usually one or more operators. Expressions are evaluated to produce a result. For example, assuming i and j are ints, then i + j is an expression and yields the sum of the two int values.
  
  
• angle brackets : <>
  
  
• quotation marks : ""
  
  
• curly braces : {}
  
  
• operator : 運算子
  
  
• operand : 運算元
  
  
• assignment
  
  Obliterates an object’s current value and replaces that value by a new one.
  
  
• comments : 註解
  
  
• statement : wiki
  
  The new part of this program is the while statement.A while has the form
  
  while (condition)
      statement
  
  A while executes by(alternately) testing the condition and executing the associated
  statement until the condition is false.A condition is an expression that yields a result
  that is either true or false..So long as condition is true, statement is executed.
  

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讀書心得 - C++ Primer (5th Edition) - Chapter 2 (1)