#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define _KEY_WORD_END "waiting for your expanding"
typedef struct
{
int typenum;
char *word;
}WORD;
char input[255];
char token[255]="";
int p_input;
int p_token;
char ch;
char *rwtab[]={"begin","if","while","do","end",_KEY_WORD_END};
//输入缓冲区中读取一个字符到ch中
char m_getch()
{
ch=input[p_input];
p_input=p_input+1;
return(ch);
}
//去掉空白符号
void getbc()
{
while(ch==' '||ch==10)
{
ch=input[p_input];
p_input=p_input+1;
}
}
//拼接单词
void concat()
{
token[p_token]=ch;
p_token=p_token+1;
token[p_token]='\0';
}
//判断是否字母
int letter()
{
if((ch >= 'a' && ch <= 'z' )|| (ch >= 'A' && ch <= 'Z')) return 1;
else return 0;
}
//判断是否数字
int digit()
{
if(ch >= '0' && ch <= '9') return 1;
else return 0;
}
//检索关键字表格
int reserve()
{
int i=0;
while(strcmp(rwtab[i],_KEY_WORD_END))
{
if(!strcmp(rwtab[i],token))
{
return i+1;
}
i=i+1;
}
return 10;
}
//回退一个字符
void retract()
{
p_input=p_input-1;
}
//数字转换二进制，自己补全
char *dtb()
{
return NULL;
}
//读取标识符
WORD *scaner()
{
WORD *myword=new WORD;
myword->typenum=10;
myword->word="";
p_token=0;
m_getch();
getbc();
if(letter())
{
while(letter()||digit())
{
concat();
m_getch();
}
retract();
myword->typenum=reserve();
myword->word=token;
return(myword);
}
else if(digit())
{
while(digit())
{
concat();
m_getch();
}
retract();
myword->typenum=11;
myword->word=token;
return(myword);
}
else switch (ch)
{
case '=':
m_getch();
if (ch == '=')
{
myword->typenum = 39;
myword->word = "==";
return(myword);
}
retract();
myword->typenum = 21;
myword->word = "=";
return(myword);
break;
case '+':
myword->typenum = 22;
myword->word = "+";
return(myword);
break;
case '-':
myword->typenum = 23;
myword->word = "=";
return(myword);
break;
case '*':
myword->typenum = 24;
myword->word = "*";
return(myword);
break;
case '/':
myword->typenum = 25;
myword->word = "/";
return(myword);
break;
case '(':
myword->typenum = 26;
myword->word = "(";
return(myword);
break;
case ')':
myword->typenum = 27;
myword->word = ")";
return(myword);
break;
case '[':
myword->typenum = 28;
myword->word = "[";
return(myword);
break;
case ']':
myword->typenum = 29;
myword->word = "]";
return(myword);
break;
case '{':
myword->typenum = 30;
myword->word = "{";
return(myword);
break;
case '}':
myword->typenum = 31;
myword->word = "}";
return(myword);
break;
case ',':
myword->typenum = 32;
myword->word = ",";
return(myword);
break;
case ':':
m_getch();
if(ch=='=')
{
myword->typenum=18;
myword->word=":=";
return(myword);
}
myword->typenum = 33;
myword->word = ":";
return(myword);
break;
case ';':
myword->typenum = 34;
myword->word = ";";
return(myword);
break;
case '>':
m_getch();
if (ch == '=')
{
myword->typenum = 37;
myword->word = ">=";
return(myword);
}
retract();
myword->typenum = 35;
myword->word = ">";
return(myword);
break;
case '<':
m_getch();
if (ch == '=')
{
myword->typenum = 38;
myword->word = ">=";
return(myword);
}
retract();
myword->typenum = 36;
myword->word = "<";
return(myword);
break;
case '!':
m_getch();
if (ch == '=')
{
myword->typenum = 40;
myword->word = "!=";
return(myword);
}
retract();
myword->typenum = -1;
myword->word = "ERROR";
return(myword);
break;
case '\0':
myword->typenum = 1000;
myword->word = "OVER";
return(myword);
break;
default:
myword->typenum = -1;
myword->word = "ERROR";
return(myword);
break;
}
}
int main()
{
int over=1;
WORD *oneword=new WORD;
printf("Enter Your words(end with #):");
scanf("%[^#]s",input);
p_input=0;
printf("Your words:\n%s\n",input);
while(over<1000&&over!=-1)
{
oneword=scaner();
if(oneword->typenum<1000)
printf("(%d,%s)",oneword->typenum,oneword->word);
over=oneword->typenum;
}
printf("\npress#to exit:");
scanf("%[^#]s",input);
system("PAUSE"); //
}
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