Thread: Lex help - Segmentation Fault

  1. #1
    Registered User
    Join Date
    Nov 2005

    Lex help - Segmentation Fault

    I'm using Lex to do lexical analysis, in the below code when it gets to returning 1 (on the EOF rule), it quits with a segmentation fault.

    Any idea whats causing this?

    I don't actually need the 1 value, i just need the program generated to exit the subroute, keeping the two arrays in memory so they can be accessed by my parsing program.

    any ideas?


    #include <math.h>
    #include <stdio.h>
    /* codes for the different tokens */
    #define MYEOF 0
    #define IDENTIFIER 1
    #define NUMBER 2
    #define INTEGER 3
    #define CHAR 4
    int input[64]; /* buffer for holding the input */
    char *input_value[64];
    int count = 0; /*int to point to the next array location to be writen to*/
    void Set_Arrays(int token, char *Value);
    "int"			{Set_Arrays(INTEGER, yytext);}
    "char"			{Set_Arrays(CHAR, yytext);}
    "EOF"                   {Set_Arrays(MYEOF, yytext); return 1;}
    [0-9]+			{Set_Arrays(NUMBER, yytext);}
    [a-zA-Z][0-9a-zA-Z]*	{Set_Arrays(IDENTIFIER, yytext);}
    "("			{Set_Arrays('(', yytext);}
    ")"			{Set_Arrays(')', yytext);}
    "+"			{Set_Arrays('+', yytext);}
    "-"			{Set_Arrays('-', yytext);}
    "*"			{Set_Arrays('*', yytext);}
    "/"			{Set_Arrays('/', yytext);}
    "="			{Set_Arrays('=', yytext);}
    ";"			{Set_Arrays(';', yytext);}
    "{"			{Set_Arrays('{', yytext);}
    "}"			{Set_Arrays('}', yytext);}
    [ \t\n]+		{/* eat up white space */}
    .			{printf("Unrecognized character: %s\n", yytext);}
    void Set_Arrays(int token, char *value){
         input[count] = token;
         input_value[count] = value;
         printf("Tokeen = %d \n", input[count]);
         printf("Value = %s \n", input_value[count]);
    yywrap() {} /* For Linux compatibility */

  2. #2
    Unregistered User
    Join Date
    Sep 2005
    is that C code? I don't think it will compile, maybe there's a problem with the formatting.

  3. #3
    Frequently Quite Prolix dwks's Avatar
    Join Date
    Apr 2005
    it quits with a segmentation fault.
    I think it compiles. Or do you mean the compiler quits with a seg fault?

    I think the file gets pre-parsed by Lex, whatever that is, which turns it into valid C code.

    Or are you using digraphs? No, even then I don't think that would compile.

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