stack.c

一个编译器的例子,基于c语言,在linux下开发 现在了简单的c语言例子

#include<stdlib.h>
#include "struct.h"

float stack[2048];
int valueError=0;
int pointer =-1;

void push(float node)
{
    //printf("pushed: %f\n", node);
    if(pointer>254){
       valueError=1;  
       return;
    }
    pointer++;      
    stack[pointer]=node;  
}

float pop()
{
   if(pointer<0) {
      valueError=-1;
      return -10000;
   }
   //printf("poped: %f\n", stack[pointer]);
   pointer--;
   return stack[pointer+1];
}

void empty()
{
  pointer=-1;
}

void calcuExp(symnode * node)
{ 
    float a, b;
     if(node==NULL) return;
     calcuExp(node->next);
     calcuExp(node->sibling);
     
     if(strcmp(node->name, "INT_V")==0)
     {
           //printf("\npushing %d\n",atoi(node->value));
           push( atoi(node->value));
     }	
     if(strcmp(node->name, "CHAR_V")==0)
     {
           //printf("\npushing %d\n",atoi(node->value));
           push( (int)(node->value[1]));
     }	   
     if(strcmp(node->name, "ID")==0){
           valueError=2; push(1);
     }
     if(strcmp(node->name, "FLT_V")==0){
        
          //printf(" pushed: %s\n ",node->value);
          valueError=3; 
	  push(atof(node->value));
     }
   
     if(strcmp(node->name, "OP")==0){
        if(strcmp(node->value, "+")==0){
	    b = pop();
	    a=pop();
	    push(a+b);
	}
        if(strcmp(node->value, "-")==0){
	    b = pop();
	    a=pop();
	    push(a-b);
	}
        if(strcmp(node->value, "*")==0){
	    b = pop();
	    a=pop();
	    //printf("\npoped a:%d, b:%d\n", a, b);
	    push(a*b);
	}
        if(strcmp(node->value, "/")==0){
	    b = pop();
	    a=pop();
	    push(a/b);
	}
        if(strcmp(node->value, "%")==0){
	    b = pop();
	    a=pop();
	    push((int)a%(int)b);
	}
     }
}     
     
int errorOccur()
{
   int status;
   status=valueError;
   valueError=0;
   pointer=0;
   return status;
}
 
float getConstant(symnode *node)
{
        empty();
	calcuExp(node);
	return pop();
}