#include<stdlib.h>
#include<string.h>
#include<dos.h>
char A[20];//分析栈
char B[20];//剩余串
char v1[20] = { 'i','+','*','(',')','#' };//终结符
char v2[20] = { 'E','G','T','S','F' };//非终结符
int j = 0, b = 0, top = 0, l;//L为输入串长度
typedef struct type//产生式类型定义
{
char origin;//大写字符
char array[5];//产生式右边字符
int length;//字符个数
}type;
type e, t, g, g1, s, s1, f, f1;//结构体变量
type C[10][10];//预测分析表
void print()//输出分析栈
{
int a;//指针
for (a = 0; a <= top + 1; a++)
printf("%c", A[a]);
printf("\t\t");
}/*print*/
void print1()/*输出剩余串*/
{
int j;
for (j = 0; j<b; j++)/*输出对齐符*/
printf(" ");
for (j = b; j <= l; j++)
printf("%c", B[j]);
printf("\t\t\t"); }/*print1*/
void main()
{
int m, n, k = 0, flag = 0, finish = 0;
char ch, x;
type cha;/*用来接受C[m][n]*/ /*把文法产生式赋值结构体*/
e.origin = 'E';
strcpy(e.array, "TG");
e.length = 2;
t.origin = 'T';
strcpy(t.array, "FS");
t.length = 2;
g.origin = 'G';
strcpy(g.array, "+TG");
g.length = 3;
g1.origin = 'G';
g1.array[0] = '^';
g1.length = 1;
s.origin = 'S';
strcpy(s.array, "*FS");
s.length = 3;
s1.origin = 'S';
s1.array[0] = '^';
s1.length = 1;
f.origin = 'F';
strcpy(f.array, "(E)");
f.length = 3;
f1.origin = 'F';
f1.array[0] = 'i';
f1.length = 1;
for (m = 0; m <= 4; m++)/*初始化分析表*/
for (n = 0; n <= 5; n++)
C[m][n].origin = 'N';/*全部赋为空*/
/*填充分析表*/
C[0][0] = e; C[0][3] = e;
C[1][1] = g; C[1][4] = g1; C[1][5] = g1;
C[2][0] = t; C[2][3] = t;
C[3][1] = s1; C[3][2] = s; C[3][4] = C[3][5] = s1;
C[4][0] = f1; C[4][3] = f;
printf("提示:本程序只能对由'i','+','*','(',')'构成的以'#'结束的字符串进行分析,\n");
printf("请输入要分析的字符串:");
do/*读入分析串*/
{
scanf("%c", &ch);
if ((ch != 'i') && (ch != '+') && (ch != '*') && (ch != '(') && (ch != ')') && (ch != '#'))
{
printf("输入串中有非法字符\n");
exit(1);
}B[j] = ch;
j++;
}while (ch != '#');
l = j;/*分析串长度*/
ch = B[0];/*当前分析字符*/
A[top] = '#';
A[++top] = 'E';/*'#','E'进栈*/
printf("步骤\t\t分析栈\t\t剩余字符\t\t所用产生式\n");
do {
x = A[top--];/*x为当前栈顶字符*/
printf("%d", k++);
printf("\t\t");
for (j = 0; j <= 5; j++)/*判断是否为终结符*/
if (x == v1[j])
{
flag = 1;
break; }
if (flag == 1)/*如果是终结符*/
{
if (x == '#')
{
finish = 1;/*结束标记*/
printf("acc!\n");/*接受?*/
getchar();
getchar();
exit(1);
}/*if*/
if (x == ch)
{
print();
print1();
printf("%c匹配\n", ch);
ch = B[++b];/*下一个输入字符*/
flag = 0;/*恢复标记*/ }/*if*/
else/*出错处理*/
{ print(); print1();
printf("%c出错\n", ch);/*输出出错终结符*/
exit(1); }/*else*/
}/*if*/
else/*非终结符处理*/
{
for (j = 0; j <= 4; j++)
if (x == v2[j])
{
m = j;/*行号*/
break;
}
for (j = 0; j <= 5; j++)
if (ch == v1[j])
{ n = j;/*列号*/ break;
}
cha = C[m][n];
if (cha.origin != 'N')/*判断是否为空*/
{ print();
print1();
printf("%c->", cha.origin);/*输出产生式*/
for (j = 0; j<cha.length; j++)
printf("%c", cha.array[j]);
printf("\n");
for (j = (cha.length - 1); j >= 0; j--)/*产生式逆序入栈*/
A[++top] = cha.array[j];
if (A[top] == '^')/*为空则不进栈*/
top--;
}/*if*/
else/*出错处理*/ { print();
print1();
printf("%c出错\n", x);/*输出出错非终结符*/
exit(1);
}/*else*/
}/*else*/
}while (finish == 0); }/*main*/
