Euphoria if...elsif...else...endif 語句
if 語句:
if語句由一個布爾表達式後跟一個或多個語句。
語法:
if語句的語法是：
if expression then -- Statements will execute if the expression is true end if |
if 布爾表達式的值為true，那麼裡麵的代碼塊，if語句會被執行。如果不是第一組結束後的代碼，if 語句將被執行。
示例:
#!/home/euphoria-4.0b2/bin/eui
integer a = 10
integer b = 20
if (a + b) < 40 then
printf(1, "%s\n", {"This is true if statement!"})
end if
if (a + b) > 40 then
printf(1, "%s\n", {"This is not true if statement!"})
end if
|
這將產生以下結果：
This is true if statement! |
if...else 語句:
if語句後麵可以通過一個可選的else語句，布爾表達式為 false 時執行。
語句:
if...else 語句的語法是:
if expression then -- Statements will execute if the expression is true else -- Statements will execute if the expression is false end if |
示例:
#!/home/euphoria-4.0b2/bin/eui
integer a = 10
integer b = 20
if (a + b) < 40 then
printf(1, "%s\n", {"This is inside if statement!"})
else
printf(1, "%s\n", {"This is inside else statement!"})
end if
|
這將產生以下結果：
This is inside if statement! |
if...elsif...else 語句:
if語句後麵可以跟任意數量的可選elsif...else語句，這是非常有用的，以測試各種條件下使用單個if...elsif語句。
語法:
if...elsif...else 語法是:
if expression1 then -- Executes when the Boolean expression 1 is true elsif expression2 then -- Executes when the Boolean expression 2 is true elsif expression3 then -- Executes when the Boolean expression 3 is true else -- Executes when none of the above condition is true. end if |
示例:
#!/home/euphoria-4.0b2/bin/eui
integer a = 10
integer b = 20
if (a + b) = 40 then
printf(1, "Value of (a + b ) is %d\n", a + b )
elsif (a + b) = 45 then
printf(1, "Value of (a + b ) is %d\n", a + b )
elsif (a + b) = 30 then
printf(1, "Value of (a + b ) is %d\n", a + b )
else
printf(1, "Value of (a + b ) is %d\n", 0 )
end if
|
這將產生以下結果：
Value of (a + b ) is 30 |
if...label...then 語句:
if 語句可以有一個標簽子句之前 then 關鍵字。需要注意的是elsif 子句不能有一個label。
if label塊和標簽名稱必須用雙引號的字符串常量，有單個或多個字。label關鍵字是區分大小寫的，應該寫成label。 .
語法:
label 子句語法：
if expression label "Label Name" then -- Executes when the boolean expression is true end if |
例子:
#!/home/euphoria-4.0b2/bin/eui
integer a = 10
integer b = 20
if (a + b) = 40 label "First IF Block" then
printf(1, "Value of (a + b ) is %d\n", a + b )
elsif (a + b) = 45 then
printf(1, "Value of (a + b ) is %d\n", a + b )
elsif (a + b) = 30 then
printf(1, "Value of (a + b ) is %d\n", a + b )
else
printf(1, "Value of (a + b ) is %d\n", 0 )
end if
|
這將產生以下結果：
Value of (a + b ) is 30 |
嵌套 if...else 語句:
它始終是合法的嵌套if-else語句。這意味著可以有一個在另一個 if-else 語句中使用 if-else 語句。
語法:
嵌套 if...else 語法是:
if expression1 then
-- Executes when the boolean expression1 is true
if expression2 then
-- Executes when the boolean expression2 is true
end if
end if
|
例子:
#!/home/euphoria-4.0b2/bin/eui
integer a = 10
integer b = 20
integer c = 0
if c = 0 then
printf(1, "Value of c is equal to %d\n", 0 )
if (a + b) = 30 then
printf(1, "Value of (a + b ) is equal to %d\n", 30)
else
printf(1, "Value of (a + b ) is equal to %d\n", a + b )
end if
else
printf(1, "Value of c is equal to %d\n", c )
end if
|
這將產生以下結果：
Value of c is equal to 0 Value of (a + b ) is equal to 30 |
