Error in lex program?
I was making this very simple lex program (just an introductory program). But on compiling lex.yy.c, I am getting this error as:
inToPostfix.l:26: error: ‘struct stac开发者_如何学运维koperand’ has no member named ‘top’
inToPostfix.l:32: error: ‘struct stackoperator’ has no member named ‘top’....
I could not make any reason for this error as I already have defined top in the specified structure. Can you see any reason for it?
Code is posted at http://pastebin.com/d5f059c1d
Here is a diff against your original. It fixes all the problems when compiling:
--- orig.l 2009-11-09 14:55:47.414002041 -0500
+++ kk.l 2009-11-09 14:54:53.386385539 -0500
@@ -1,14 +1,15 @@
%{
#include<stdio.h>
%}
+ int precedence(char a,char b);
struct stackoperator{
char stack[10];
- int top =-1;
+ int top;
};
struct stackoperand{
int stack[10][2];
- int top =-1;
+ int top;
};
struct stackoperator operator;
struct stackoperand operand;
@@ -29,6 +30,7 @@
}
[ \t] ;
[\n] {
+ char ch;
while(operator.top!=-1)
{
ch=pop();
Move line 3 to line 16.
You also need to remove the initializers from the structure declarations - at least for C (but the C++ compiler didn't think much of it either).
struct stackoperator
{
char stack[10];
int top =-1;
};
To:
struct stackoperator
{
char stack[10];
int top;
};
In the actions, you also need to declare 'ch'.
You also need to declare your functions - I made them static. This compiles (assuming you have a C99 compiler - the designated initializers won't work with C89 compilers):
%{
#include<stdio.h>
struct stackoperator
{
char stack[10];
int top;
};
struct stackoperand
{
int stack[10][2];
int top;
};
struct stackoperator operator = { .top = -1 };
struct stackoperand operand = { .top = -1 };
int num=0;
static void push(int num,int flag);
static int pop(void);
static int precedence(char a,char b);
%}
%%
[0-9] {num=num*10+(*yytext-'0');push(num,1);}
[-+*/] {
if(precedence(operator.top,*yytext)) {
char ch=pop();
push(ch,0);
operand.stack[operand.top][1]=1;
}
push(*yytext,0);
}
[ \t] ;
[\n] {
char ch;
while(operator.top!=-1)
{
ch=pop();
push(ch,0);
}
int i=0;
while(i<=operand.top)
{
if(operand.stack[operand.top][1]==1)
printf(" %c ",operand.stack[operand.top][0]);
else
printf(" %d ",operand.stack[operand.top][0]);
}
}
%%
static void push(int num,int flag)
{
if(flag)
{ operand.top++;
operand.stack[operand.top][0]=num;
operand.stack[operand.top][1]=0;
}
else
operator.stack[++operator.top]=num;
}
static int pop(void)
{
return operator.stack[operator.top--];
}
static int precedence(char a,char b)
{
if(operator.top==-1)
return 0;
if((a=='*'||a=='/') && (b=='+'||b=='-'))
return 1;
else
return 0;
}
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