也看了網上大神們的作品，他們的思路都好清晰啊，我只能領悟了在開始自己寫了，大部分都加了註釋。。。
爲啥用java呢，c看着vc6.0和cb就頭疼啊
修改了一下，先在空格也可以判斷了。
代碼輸入
int a = 21 ;
int b = 22 ;
int c = 0 ;
c = a + b ;
a= a * b ;
int price = 22 ;
package parser;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.lang.reflect.Array;
import java.util.Arrays;
import java.util.Stack;
//輸入文本：
//int a=21;
//int b=22;
//int c=0;
//c=a+b;
//a=a*b;
//int price=22;
public class Parser {
Stack<Object> retain = new Stack<>();
Stack<Object> token = new Stack<>();
Stack<Object> cons = new Stack<>();
Stack<Object> oper = new Stack<>();
Stack<Object> bound = new Stack<>();
public int ch;//每次獲取的ascll字符
public int code = 0;//分類碼
/**
* 1 基本字 保留字
* 2 標識符 自己的變量名
* 3 常數
* 4 算符
* 5 界符
*/
// 保留字
String[] retainword = {"int","string","float","const","do",
"switch","for","if","else","while",
"break","new","return"};
// 操作符
int operator[] = {42,43,45,47,61};
// 界符
char delimiter[] = {',','{','}',';','(',')'};
// 單詞
StringBuffer strapp = new StringBuffer();
public static void main(String[] args) {
String[] delimiters = {"(",")",";",",","",""};
new Parser().scanner();
}
// 輸入的是否是字母
public boolean isLetter(){
if ((ch>64&&ch<91)||(ch>96&&ch<123)) {
return true;
}
return false;
}
// 輸入的是否是數字
public boolean isFigure(){
if (ch>47&&ch<58){
return true;
}
return false;
}
// 輸入的是否是空格
public boolean isSpace(int ch){
if (ch==32||(char)ch==' ') {
return true;
}
return false;
}
// 是否是操作符
public boolean isOperator(int ch){
for (int i : operator) {
if(ch==i){
oper.push((char)ch);
return true;
}
}
return false;
}
// 是否是界符
public boolean isDelimiters(int ch){
for (char c : delimiter) {
if((char)ch==c){
bound.push((char)ch);
return true;
}
}
return false;
}
// 單詞判斷
public int isRetainW(){
for (String string : retainword) {
if (strapp.toString().equals(string)) {
retain.push(strapp.toString());
return 1;
}else if(strapp.length() != 0){
if(strapp.charAt(0)>='0' && strapp.charAt(0)<='9'){
cons.push(strapp.toString());
return 3;
}
}
}
String a = strapp.toString();
// 如果拼接的字符串爲0的話就放棄這個字符串，因爲它是代碼中的空格
if(a.equals("")){
// System.out.println(a+"!!!");
return 0;
}
token.push(strapp.toString());
return 2;
}
// 字符串拼接
public void strAppend(char ch){
strapp.append(ch);
}
// 輸出結果
public void sysostr(){
code = isRetainW();
if (code!=0) {
System.out.println("("+code+","+strapp+")");
}
code = 0;
strapp.delete(0, strapp.length());
}
public void scanner(){
BufferedReader br;
try {
br = new BufferedReader(new FileReader("/Users/rqw1991/Downloads/dd.txt"));
// 讀入數據
while((ch=br.read())!=-1){
/**
*
*/
// 是不是空格，不是空格繼續
if (!isSpace(ch)) {
// 是不是字母，是字母就開始進入字符串的拼接
if(isLetter()){
// 如果不是空格而且是字母或者數字的話就開始進行句柄的拼接
if((isLetter()||isFigure())&&(!isSpace(ch))){
strAppend((char)ch);
}
}else if(isFigure()==true&&(!isSpace(ch))){
strAppend((char)ch);
}else if(isFigure()&&(!isSpace(ch))){
strAppend((char)ch);
}
// else if(ch == 61){
// if((strapp.length() != 0 )&& (strapp.charAt(0) == '=')){
// strapp.append((char)ch);
// System.out.println("("+4+",'"+strapp+"')");
// strapp.delete(0, strapp.length());
// }else{
// strapp.append((char)ch);
// }
// }
else if(isDelimiters(ch)&&(!isSpace(ch))){
sysostr();
System.out.println("("+4+","+(char) ch+")");
}
else if(isOperator(ch)&&(!isSpace(ch))){
sysostr();
System.out.println("("+5+","+(char) ch+")");
}
}else{
sysostr();
}
}
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally {
int rsize = retain.size();
System.out.println("1:"+rsize);
for (int i = 0; i < rsize; i++) {
System.out.print(i+":"+retain.pop()+" ");
}
System.out.println();
int tsize = token.size();
System.out.println("2:"+token.size());
for (int i = 0; i < tsize; i++) {
System.out.print(i+":"+token.pop()+" ");
}
System.out.println();
int csize = cons.size();
System.out.println("3:"+cons.size());
for (int i = 0; i < csize; i++) {
System.out.print(i+":"+cons.pop()+" ");
}
System.out.println();
int osize = oper.size();
System.out.println("4:"+oper.size());
for (int i = 0; i < osize; i++) {
System.out.print(i+":"+oper.pop()+" ");
}
System.out.println();
int bsize = bound.size();
System.out.println("5:"+bound.size());
for (int i = 0; i < bsize; i++) {
System.out.print(i+":"+bound.pop()+" ");
}
}
}
}
package parser;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.lang.reflect.Array;
import java.util.Arrays;
import java.util.Stack;
//輸入文本：
//int a=21;
//int b=22;
//int c=0;
//c=a+b;
//a=a*b;
//int price=22;
public class Parser {
Stack<Object> retain = new Stack<>();
Stack<Object> token = new Stack<>();
Stack<Object> cons = new Stack<>();
Stack<Object> oper = new Stack<>();
Stack<Object> bound = new Stack<>();
public int ch;//每次獲取的ascll字符
public int code = 0;//分類碼
/**
* 1 基本字 保留字
* 2 標識符 自己的變量名
* 3 常數
* 4 算符
* 5 界符
*/
// 保留字
String[] retainword = {"int","string","float","const","do",
"switch","for","if","else","while",
"break","new","return"};
// 操作符
int operator[] = {42,43,45,47,61};
// 界符
char delimiter[] = {',','{','}',';','(',')'};
// 單詞
StringBuffer strapp = new StringBuffer();
public static void main(String[] args) {
String[] delimiters = {"(",")",";",",","",""};
new Parser().scanner();
}
// 輸入的是否是字母
public boolean isLetter(){
if ((ch>64&&ch<91)||(ch>96&&ch<123)) {
return true;
}
return false;
}
// 輸入的是否是數字
public boolean isFigure(){
if (ch>47&&ch<58){
return true;
}
return false;
}
// 輸入的是否是空格
public boolean isSpace(int ch){
if (ch==32||(char)ch==' ') {
return true;
}
return false;
}
// 是否是操作符
public boolean isOperator(int ch){
for (int i : operator) {
if(ch==i){
oper.push((char)ch);
return true;
}
}
return false;
}
// 是否是界符
public boolean isDelimiters(int ch){
for (char c : delimiter) {
if((char)ch==c){
bound.push((char)ch);
return true;
}
}
return false;
}
// 單詞判斷
public int isRetainW(){
for (String string : retainword) {
if (strapp.toString().equals(string)) {
retain.push(strapp.toString());
return 1;
}else if(strapp.length() != 0){
if(strapp.charAt(0)>='0' && strapp.charAt(0)<='9'){
cons.push(strapp.toString());
return 3;
}
}
}
String a = strapp.toString();
// 如果拼接的字符串爲0的話就放棄這個字符串，因爲它是代碼中的空格
if(a.equals("")){
// System.out.println(a+"!!!");
return 0;
}
token.push(strapp.toString());
return 2;
}
// 字符串拼接
public void strAppend(char ch){
strapp.append(ch);
}
// 輸出結果
public void sysostr(){
code = isRetainW();
if (code!=0) {
System.out.println("("+code+","+strapp+")");
}
code = 0;
strapp.delete(0, strapp.length());
}
public void scanner(){
BufferedReader br;
try {
br = new BufferedReader(new FileReader("/Users/rqw1991/Downloads/dd.txt"));
// 讀入數據
while((ch=br.read())!=-1){
/**
*
*/
// 是不是空格，不是空格繼續
if (!isSpace(ch)) {
// 是不是字母，是字母就開始進入字符串的拼接
if(isLetter()){
// 如果不是空格而且是字母或者數字的話就開始進行句柄的拼接
if((isLetter()||isFigure())&&(!isSpace(ch))){
strAppend((char)ch);
}
}else if(isFigure()==true&&(!isSpace(ch))){
strAppend((char)ch);
}else if(isFigure()&&(!isSpace(ch))){
strAppend((char)ch);
}
// else if(ch == 61){
// if((strapp.length() != 0 )&& (strapp.charAt(0) == '=')){
// strapp.append((char)ch);
// System.out.println("("+4+",'"+strapp+"')");
// strapp.delete(0, strapp.length());
// }else{
// strapp.append((char)ch);
// }
// }
else if(isDelimiters(ch)&&(!isSpace(ch))){
sysostr();
System.out.println("("+4+","+(char) ch+")");
}
else if(isOperator(ch)&&(!isSpace(ch))){
sysostr();
System.out.println("("+5+","+(char) ch+")");
}
}else{
sysostr();
}
}
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally {
int rsize = retain.size();
System.out.println("1:"+rsize);
for (int i = 0; i < rsize; i++) {
System.out.print(i+":"+retain.pop()+" ");
}
System.out.println();
int tsize = token.size();
System.out.println("2:"+token.size());
for (int i = 0; i < tsize; i++) {
System.out.print(i+":"+token.pop()+" ");
}
System.out.println();
int csize = cons.size();
System.out.println("3:"+cons.size());
for (int i = 0; i < csize; i++) {
System.out.print(i+":"+cons.pop()+" ");
}
System.out.println();
int osize = oper.size();
System.out.println("4:"+oper.size());
for (int i = 0; i < osize; i++) {
System.out.print(i+":"+oper.pop()+" ");
}
System.out.println();
int bsize = bound.size();
System.out.println("5:"+bound.size());
for (int i = 0; i < bsize; i++) {
System.out.print(i+":"+bound.pop()+" ");
}
}
}
}