if 语句:
if语句由一个布尔表达式后跟一个或多个语句。
语法:
if语句的语法是：
if expression then -- Statements will execute if the expression is true end if |
if 布尔表达式的值为true，那么里面的代码块，if语句会被执行。如果不是第一组结束后的代码，if 语句将被执行。
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
|
这将产生以下结果：
This is true if statement! |
if...else 语句:
if语句后面可以通过一个可选的else语句，布尔表达式为 false 时执行。
语句:
if...else 语句的语法是:
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
|
这将产生以下结果：
This is inside if statement! |
if...elsif...else 语句:
if语句后面可以跟任意数量的可选elsif...else语句，这是非常有用的，以测试各种条件下使用单个if...elsif语句。
语法:
if...elsif...else 语法是:
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
|
这将产生以下结果：
Value of (a + b ) is 30 |
if...label...then 语句:
if 语句可以有一个标签子句之前 then 关键字。需要注意的是elsif 子句不能有一个label。
if label块和标签名称必须用双引号的字符串常量，有单个或多个字。label关键字是区分大小写的，应该写成label。 .
语法:
label 子句语法：
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
|
这将产生以下结果：
Value of (a + b ) is 30 |
嵌套 if...else 语句:
它始终是合法的嵌套if-else语句。这意味着可以有一个在另一个 if-else 语句中使用 if-else 语句。
语法:
嵌套 if...else 语法是:
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
|
这将产生以下结果：
Value of c is equal to 0 Value of (a + b ) is equal to 30 |
