词法分析程序

词法分析程序的功能：通过用户输入的关键字及其他保留字符，输出它本身及它的种别码
符号与种别码对照表如下

单词符号	种别码	单词符号	种别码
begin	1	:	17
if	2	:=	18
then	3	<	20
while	4	<=	21
do	5	<>	22
end	6	>	23
l(l|d)*	10	>=	24
dd*	11	=	25
+	13	;	26
-	14	(	27
*	15	)	28
/	16	#	0

用文法描述词法规则：
<字母>->a/b/c.../z
<数字>->1/2/3/4/5/6/7/8/9
<标识符>->sum.....
<关键字>->begin/if/then/while/do/end
<运算符>->+,-,*,/,:,:=,<,<=,<>,>,>=,=
<界符>->;|(|)|[|]|{|}
已完成的代码如下：
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
char word[6][5]={"begin","if","then","while","do","end"};
char word2[18][3]={"|","dd*","+","-","*","/",":",":=","<","<=","<>",">",">=","=",";","(",")","#"};
int words(char ch[][5]);
int signs(char ch[][3]);
main()
{
    char ch[10];
    printf("请输入保留字：");
    scanf("%s",ch);
    words(ch);
    signs(ch);
}
int words(char ch[][5])
{
    while(ch==''||ch==10||ch==13||ch==9)
    {
        getchar;
    }
    if(ch>='a'&&ch<='z')
    {
        switch(ch)
        {}

    }
}
int signs(char ch[][3])
{
    while(ch==''||ch==10||ch==13||ch==9)
    {
        getchar;
    }
    if(ch>='0'&&ch<='9')
    {
        switch(ch)
        {}
    }
}