<program> :
external_declaration
| program external_declaration
<external_declaration> : //外部声明
function_definition
| declaration
<type_specifier> : //类型
Void
|char
|int
|float
|double
<iteration_statement>: //循环
|while '(' expression ')' statement
| for '(' expression_statement expression_statement ')' statement
<identifier> : //标识符 头文件
Include
| define
|stdio.h
|math.h
|stdlib.h
|time.h
|string.h
|main ‘(‘ ‘)
<statement> : //声明
udge_statement
|jump_statement
|iteration_statement
|selection_statement
<Judge_statement> : //判断
selection_statement
: if '(' expression ')' statement
|if'(' expression ')' statement ELSE statement
| logical_or_expression '?' expression ':' conditional_expression
constant_expression : //条件
conditional_expression