算符优先分析法(gaiguo).txt

关于算法优先分析方法的相关代码

#include "stdio.h"  
#include "malloc.h"  

struct Lchar
{ 
  char char_ch; 
  struct Lchar *next;
}LLchar,*p,*h,*temp,*top,*base, *nbs;

int table[8][8]={{1,1,-1,-1,-1,1,-1,1},  
    {1,1,-1,-1,-1,1,-1,1},  
    {1,1,1,1,-1,1,-1,1},  
    {1,1,1,1,-1,1,-1,1},  
    {-1,-1,-1,-1,-1,-1,-1,0},  
    {1,1,1,1,0,1,0,1},  
    {1,1,1,1,0,1,0,1},  
    {-1,-1,-1,-1,-1,0,-1,-1}};  
//存储算符优先关系表，大于为1，小于或等于为-1，其它为0表示出 

char curchar;  
char curcmp;  
int right;  /*设置开关项，当出错时为0*/  
int i,j;  
int k;      /*比较字符在栈的位置*/  

void push(char pchar)  /*入栈函数*/  
{  
 temp=(Lchar*)malloc(sizeof(LLchar));  
 temp->char_ch=pchar;  
 temp->next=top;  
 top=temp;  
}  

void pop(void)  /*出栈函数*/  
{  
 if(top->char_ch!='#')  
  top=top->next;  
}  

int changchartoint(char ch)  /*将字符转为数字，以得到算符优先值*/  
{  
 int t;  
 switch(ch)  
 {  
  case '+':t=0;break;  
  case '-':t=1;break;  
  case '*':t=2;break;  
  case '/':t=3;break;  
  case '(':t=4;break;  
  case ')':t=5;break;  
  case 'i':t=6;break;  
  case '#':t=7;  
 }  
 return t;  
}  

void dosome(void)  
{  
 k=1;  
 for(;;)  
 {  
  curchar=h->char_ch;  
  temp=top;  
  for(;;)  
  {  
   if(temp->char_ch=='N')  
   {  
  nbs;
  p;
  temp=temp->next;  
    k++;  
   }  
   else  
   {  
    curcmp=temp->char_ch;  
    break;  
   }  
  }  
  printf("\n%d\t%d\t",table[i][j],k);  
  temp=top;  
  for(;;)    /*打印栈*/  
  {  
   printf("%c",temp->char_ch);  
   if(temp->char_ch=='#')  
    break;  
   else  
    temp=temp->next;  
  }  
  printf("\t");  
  temp=h;  
  for(;;)    /*打印待比较的字符*/  
  {  
   printf("%c",temp->char_ch);  
     
   if(temp->char_ch=='#')  
    break;  
   else  
    temp=temp->next;  
  }  
  i=changchartoint(curcmp);  
  j=changchartoint(curchar);  
  if(table[i][j]==0)  /*算符优先值为空*/  
  {  
   printf("\n%d\t%d\t%c\t%c\terror1",table[i][j],k,curcmp,curchar);  
   right=0;  
   break;  
  }  
  else                 /*算符优先值不为空*/  
  {  
   if(table[i][j]<0)   /*算符优先值为-1，移进*/  
   {  
    if(curchar=='#')   /*待比较字符为空*/  
    {  
     if(k==2)          /*当前比较字符在栈的位置为两个元素*/  
      break;  
     else  
     {  
      printf("\n%d\t%d\t%c\t%c\terror2",table[i][j],k,curcmp,curchar);  
      right=0; 
      break;  
     }  
    }  
    push(curchar);  
    k=1;  
    curcmp=curchar;  
    h=h->next;  
   }  
   else              /*算符优先值为1，归约*/  
   {  
    if(curcmp=='i')  /*当前比较为i,出栈一次*/  
     pop();  
    else             /*当前比较不为i,出栈三次*/  
    {  
     pop();  
     pop();  
     pop();  
    }  
    push('N');       /*归约到N*/  
    k=1;  
   }  
  }  
 }  
}  
void main(void)  
{  
 char ch;  
 right=1;  
 base=(Lchar*)malloc(sizeof(LLchar));  
 base->next=NULL; 
 base->char_ch='#';  
 top=base;  
 h=(Lchar*)malloc(sizeof(LLchar));  
 h->next=NULL;  
 p=h;  
 do{                 /*输入待比较字符串，以'#'结束*/  
  ch=getchar();  
  putchar(ch); 	  
  if(ch=='i'||ch=='+'||ch=='-'||ch=='*'||ch=='/'||ch=='('||ch==')'||ch=='#')  
  {  
   temp=(Lchar*)malloc(sizeof(LLchar));  
   temp->next=NULL;  
   temp->char_ch=ch;  
   h->next=temp;  
   h=h->next;  
  }  
  else  
  {  
   temp=p->next;  
   printf("\nInput a wrong char!Input again:\n");  
   for(;;)  
{      
    if (temp!=NULL)  
     printf("%c",temp->char_ch);        
    else  
     break;  
    temp=temp->next;  
   }  
  }  
 }while(ch!='#');      /*输入待比较字符串，以'#'结束*/  
 p=p->next;  
 h=p;  
 dosome();             /*开始识别*/  
 if(right)  
  printf("\nOK!\n");  
 else  
  printf("\nError!\n");  
 getchar();  
}