词法分析.cpp

词法分析程序。可实现对C语言的词法分析,关键字32个,包含了C的绝大部分运算、限界符,主要是对文件进行读、写操作,节省内存消耗,是一个不错的词法分析程序。

#include<iostream>
#include<fstream>
#include<stdlib.h>
#include<string>
using namespace std;
#define MAX 100
struct Word{
	char spelling[50];
};
Word word;
/*struct ID{
    char *id[MAX];
	int point1;
};
ID SIGN;
struct NUMBER{
	char *num[MAX];
	int point2;
};
NUMBER NUM;*/
void main(){
	char c;
	//char *s=new char;
	cout<<"03级计算机一班王强"<<endl<<"学号:200345003086"<<endl;
//	cout<<"输入要打开文件的路径:";
//	cin>>s;
 	char *ID[MAX];ID[0]=NULL;
    char *NUM[MAX];NUM[0]=NULL;
	int pos=0,point1=0,point2=0,i,j;
	char *name[36]={"  ","and","array","begin","bool","call","case",
		"char","constant","dim","do","else","end","false","for",
		"if","input","integer","not","of","or","output","procedure",
		"program","read","real","repeat","set","stop","then",
		"to","true","until","var","while","write"};
	fstream f("TEST1",ios::in);
	f.seekp(-1,ios::end);
	long posEnd=f.tellp();
	f.seekp(0,ios::beg);
	f.get(c);
	while(f.tellp()!=posEnd){
		if(c==' '||c=='\n')f.get(c);	
		else{
			switch(c){
			case '(':cout<<"(39 , - )"<<"   ";break;
			case ')':cout<<"(40 , - )"<<"   ";break;
			case '*':
				f.get(c);
				if(c=='/')cout<<"(42 , - )"<<"   ";
				else {cout<<"(41 , - )"<<"   ";f.seekp(-1,ios::cur);}
				break;
			case '+':cout<<"(43 , - )"<<"   ";break;
			case ',':cout<<"(44 , - )"<<"   ";break;
			case '-':cout<<"(45 , - )"<<"   ";break;
			case '.':
				f.get(c);
				if(c=='.')cout<<"(47 , - )"<<"   ";
				else {cout<<"(46 , - )"<<"   ";f.seekp(-1,ios::cur);}
				break;
			case '/':
				f.get(c);
				if(c=='*')cout<<"(49 , - )"<<"   ";
				else {cout<<"(48 , - )"<<"   ";f.seekp(-1,ios::cur);}
				break;
			case ':':
				f.get(c);
				if(c=='=')cout<<"(51 , - )"<<"   ";
				else {cout<<"(50 , - )"<<"   ";f.seekp(-1,ios::cur);}
				break;
			case ';':cout<<"(52 , - )"<<"   ";break;
			case '<':
				f.get(c);
				if(c=='=')cout<<"(54 , - )"<<"   ";
				else if(c=='>')cout<<"(55 , - )"<<"   ";
					else{cout<<"(53 , - )"<<"   ";f.seekp(-1,ios::cur);}
				break;
			case '=':cout<<"(56 , - )"<<"   ";break;
			case '>':
				f.get(c);
				if(c=='=')cout<<"(58 , - )"<<"   ";
				else {cout<<"(57 , - )"<<"   ";f.seekp(-1,ios::cur);}
				break;
			case '[':cout<<"(59 , - )"<<"   ";break;
			case ']':cout<<"(60 , - )"<<"   ";break;
			}
			if(c>='a'&&c<='z'||c>='A'&&c<='Z'){
				word.spelling[pos]=c;
				pos++;
				f.get(c);
				if(c<='0'||c>='9'&&c<='A'||c>='z'){
					for(i=1;i<=37;i++){
						if(strcmp(word.spelling,name[i])==0){
							cout<<"("<<i<<" , - )"<<"   ";break;
						}
					}
					if(i>37){
						for(j=0;j<=point1;j++){
							if(strcmp(word.spelling,ID[j])==0)
								cout<<"("<<36<<" , "<<j+1<<" )"<<"   ";
						}
						if(j>point1){
							strcpy(ID[point1],word.spelling);
							point1++;
						}
					}
					for(i=0;i<=pos;i++)word.spelling[i]=NULL;
					pos=0;
				}
			}
			else if(c>='0'&&c<='9'){
				word.spelling[pos]=c;
				pos++;
				f.get(c);
				if(c<='0'||c>='9'){
					for(j=0;j<=point2;j++){
						if(strcmp(word.spelling,NUM[j])==0)
							cout<<"("<<37<<" , "<<j+1<<" )"<<"   ";
					}
					if(j>point2){
						strcpy(NUM[point2],word.spelling);
						point2++;
					}
					for(i=0;i<=pos;i++)word.spelling[i]=NULL;
					pos=0;
				}
			}
		}
	}		
}