flex and bison: wrong output
- by user2972227
I am doing a homework using flex and bison to make a complex number calculator. But my program cannot give a correct output.
.lex file:
%option noyywrap
%{
#include<stdio.h>
#include<stdlib.h>
#include "complex_cal.h"
#define YYSTYPE complex
#include "complex_cal.tab.h"
void RmWs(char* str);
%}
/* Add your Flex definitions here */
/* Some definitions are already provided to you*/
ws [ \t]+
digits [0-9]
number (0|[1-9]+{digits}*)\.?{digits}*
im [i]
complexnum {ws}*[-]*{ws}*{number}{ws}*[+|-]{ws}*{number}{ws}*{im}{ws}*
op [-+*/()]
%%
{complexnum} {RmWs(yytext); sscanf(yytext,"%lf %lf",&(yylval.real),&(yylval.img)); return CNUMBER;}
{ws} /**/
{op} return *yytext;
%%
/* function provided to student to remove */
/* all the whitespaces from a string. */
void RmWs(char* str){
int i=0,j=0;
char temp[strlen(str)+1];
strcpy(temp,str);
while (temp[i]!='\0'){
while (temp[i]==' '){i++;}
str[j]=temp[i];
i++; j++;
}
str[j]='\0';
}
.y file:
%{
#include <stdio.h>
#include <stdlib.h>
#include "complex_cal.h"
/* prototypes of the provided functions */
complex complex_add (complex, complex);
complex complex_sub (complex, complex);
complex complex_mul (complex, complex);
complex complex_div (complex, complex);
/* prototypes of the provided functions */
int yylex(void);
int yyerror(const char*);
%}
%token CNUMBER
%left '+' '-'
%left '*' '/'
%nonassoc '(' ')'
%%
/* start: Add your grammar rules and actions here */
complexexp: complexexp '+' complexexpmultidiv {$$=complex_add($1, $3);}
| complexexp '-' complexexpmultidiv {$$=complex_sub($1, $3);}
| complexexpmultidiv {$$.real=$1.real;$$.img=$1.img;}
;
complexexpmultidiv: complexexpmultidiv '*' complexsimple {$$=complex_mul($1, $3);}
| complexexpmultidiv '/' complexsimple {$$=complex_div($1, $3);}
| complexsimple {$$.real=$1.real;$$.img=$1.img;}
;
complexsimple: '(' complexexp ')' {$$.real=$2.real;$$.img=$2.img;}
| '(' CNUMBER ')' {$$.real=$2.real;$$.img=$2.img;}
;
/* end: Add your grammar rules and actions here */
%%
int main(){ return yyparse(); }
int yyerror(const char* s){
printf("%s\n", s);
return 0;
}
/* function provided to do complex addition */
/* input : complex numbers c1, c2 */
/* output: nothing */
/* side effect : none */
/* return value: result of addition in c3 */
complex complex_add (complex c1, complex c2){
/* c1 + c2 */
complex c3;
c3.real = c1.real + c2.real;
c3.img = c1.img + c2.img;
return c3;
}
/* function provided to do complex subtraction */
/* input : complex numbers c1, c2 */
/* output: nothing */
/* side effect : none */
/* return value: result of subtraction in c3 */
complex complex_sub (complex c1, complex c2){
/* c1 - c2 */
complex c3;
c3.real = c1.real - c2.real;
c3.img = c1.img - c2.img;
return c3;
}
/* function provided to do complex multiplication */
/* input : complex numbers c1, c2 */
/* output: nothing */
/* side effect : none */
/* return value: result of multiplication in c3 */
complex complex_mul (complex c1, complex c2){
/* c1 * c2 */
complex c3;
c3.real = c1.real*c2.real - c1.img*c2.img;
c3.img = c1.img*c2.real + c1.real*c2.img;
return c3;
}
/* function provided to do complex division */
/* input : complex numbers c1, c2 */
/* output: nothing */
/* side effect : none */
/* return value: result of c1/c2 in c3 */
complex complex_div (complex c1, complex c2){
/* c1 / c2 (i.e. c1 divided by c2 ) */
complex c3;
double d;
/*divisor calculation using the conjugate of c2*/
d = c2.real*c2.real + c2.img*c2.img;
c3.real = (c1.real*c2.real + c1.img*c2.img)/d;
c3.img = (c1.img*c2.real - c1.real*c2.img)/d;
return c3;
}
.h file:
#include <string.h>
/* struct for holding a complex number */
typedef struct {
double real;
double img;
} complex;
/* define the return type of FLEX */
#define YYSTYPE complex
Script for compiling the file:
bison -d -v complex_cal.y
flex -ocomplex_cal.lex.yy.c complex_cal.lex
gcc -o complex_cal complex_cal.lex.yy.c complex_cal.tab.c
./complex_cal
Some correct sample run of the program:
input:(5+6i)*(6+1i)
output:24.000000+41.000000i
input:(7+8i)/(-3-4i)*(5+7i)
output:-11.720000-14.040000i
input:(7+8i)/((-3-4i)*(5+7i))
output:-0.128108+0.211351i
But when I run this program, the program only give an output which is identical to my input. For example, when I input (5+6i)(6+1i), it just gives (5+6i)(6+1i). Even if I input any other things, for example, input "abc" it just gives "abc" and is not syntax error. I don't know where the problem is and I hope to know how to solve it.
