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
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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
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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.
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angle brackets : <>
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quotation marks : ""
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curly braces : {}
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operator : 運算子
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operand : 運算元
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assignment
Obliterates an object’s current value and replaces that value by a new one.
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comments : 註解
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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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