Operator <（小于）

• 来源: https://www.freebasic.net/wiki/wikka.php?wakka=KeyPgOpLessThan
• 最后更新: 2022-03-14

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比较一个表达式是否小于另一个表达式

语法

declare operator < ( byref lhs as byte, byref rhs as byte ) as integer
declare operator < ( byref lhs as ubyte, byref rhs as ubyte ) as integer
declare operator < ( byref lhs as short, byref rhs as short ) as integer
declare operator < ( byref lhs as ushort, byref rhs as ushort ) as integer
declare operator < ( byref lhs as integer, byref rhs as integer ) as integer
declare operator < ( byref lhs as uinteger, byref rhs as uinteger ) as integer
declare operator < ( byref lhs as longint, byref rhs as longint ) as integer
declare operator < ( byref lhs as ulongint, byref rhs as ulongint ) as integer

declare operator < ( byref lhs as single, byref rhs as single ) as integer
declare operator < ( byref lhs as double, byref rhs as double ) as integer

declare operator < ( byref lhs as string, byref rhs as string ) as integer
declare operator < ( byref lhs as zstring, byref rhs as zstring ) as integer
declare operator < ( byref lhs as wstring, byref rhs as wstring ) as integer

declare operator < ( byref lhs as T, byref rhs as T ) as integer

用法

result = lhs < rhs

参数

lhs

要比较的左侧表达式。

rhs

要比较的右侧表达式。

T

任何指针类型。

返回值

如果左侧表达式小于右侧表达式，返回负一 (-1)；否则（大于或等于）返回零 (0)。

描述

Operator <（小于）是一个二元运算符，比较两个表达式的不等关系，并返回结果——以 Integer 形式表示的布尔值：真为负一 (-1)，假为零 (0)。参数不会以任何方式被修改。

当此运算符应用于字符串类型数据时，执行字典序/字母顺序比较（按两个字符串字符的 ASCII 数值顺序排列）。

此运算符也可以重载以接受用户定义类型。

示例

start GeSHi

Const size As Integer = 4
Dim array(size - 1) As Integer = { 1, 2, 3, 4 }

Dim index As Integer = 0
While (index < size)
   Print array(index)
   index += 1
Wend

end GeSHi

Operator >=（大于或等于）是 Operator <（小于）的互补，与 Operator Not（按位取反）组合时功能相同。

start GeSHi

   If (69 < 420) Then Print "(69 < 420) is true."
   If Not (69 >= 420) Then Print "not (69 >= 420) is true."

end GeSHi

方言差异

• 在 -lang qb 方言中，此运算符不能被重载。

与 QB 的区别

• 无

参见

• Operator >=（大于或等于）

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