if statement
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条件付きでコードを実行.
Original:
Conditionally executes code.
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コードには、いくつかの条件が存在する場合にのみ実行する必要がある場合に使用.
Original:
Used where code needs to be executed only if some condition is present.
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構文
if ( expression ) statement_true
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if ( expression ) statement_true else statement_false
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説明
expressionは、
boolに変換式でなければならない.Original:
expression shall be an expression, convertible to
bool.The text has been machine-translated via Google Translate.
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それは
trueに評価された場合、制御がstatement_trueに渡され、statement_false（存在する場合）が実行されません.Original:
If it evaluates to
true, control is passed to statement_true, statement_false (if present) is not executed.The text has been machine-translated via Google Translate.
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そうしないと、コントロールがstatement_falseに渡され、statement_trueは実行されません.
Original:
Otherwise, control is passed to statement_false, statement_true is not executed.
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キーワード
例
次の例では、
if文のいくつかの使用例を示しています
Original:
The following example demonstrates several usage cases of the
if statement
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Run this code
#include <iostream>
int main()
{
int i = 2;
if (i > 2) {
std::cout << "first is true" << '\n';
} else {
std::cout << "first is false" << '\n';
}
i = 3;
if (i == 3) std::cout << "i == 3" << '\n';
if (i != 3) std::cout << "i != 3" << '\n';
else std::cout << "i != 3 is false" << '\n';
}
出力:
first is false
i == 3
i != 3 is false