@ECHO OFF
SETLOCAL
set /a num=%random% %%100 +1
SET /a nummod2=num %% 2
IF %nummod2% == 0 (ECHO %num% is even) ELSE (ECHO %num% is odd)

GOTO :EOF

常规 IF 语法是如果[not] operand1 == operand2 somethingtodo 其中operand1和operand2都是字符串。如果字符串包含分隔符，如 Space ， Tab 或其他对批处理具有特殊含义的字符，则字符串必须为用引号括起来。

Conventional IF syntax is if [not] operand1==operand2 somethingtodo where operand1 and operand2 are both strings. If the strings contain separators like Space,Tab or other characters that have a special meaning to batch then the string must be "enclosed in quotes".

从根本上说，如果比较字符串。运算符必须是一组固定的运算符之一[== equ neq gtr geq lss leq]因此 cmd 反对 num 预期运营商的位置。

Fundamentally, if compares strings. The operator must be one of a fixed set of operators [== equ neq gtr geq lss leq] hence cmd was objecting to num where it expected an operator.

如果$ c>语句的参数，则无法在内执行计算。

A calculation cannot be performed within a if statement's parameters.

%% 是执行 mod 操作所必需的，因为％是一个特殊字符，本身需要通过％进行转义。

%% is required to perform the mod operation, since % is a special character that itself needs to be escaped by a %.

请注意， {和} 是普通字符，对批处理没有特殊意义，必须遵循备注

Note that { and } are ordinary characters with no special meaning to batch and remarks must follow

rem remark string

有一个常用的漏洞利用

::comment

实际上是一个破损的标签，可能会产生无法预料的副作用（比如结束代码块）

actually, a broken label, which can have unforeseen side-effects (like ending a code-block)