Printing an array of structs?

[blernblan]

Hey guys, so what I'm trying to do is print each member of a struct from every struct in an array. When I try to use the following code, I get an error saying "error request for member 'line' in something not a structure or union. It says this for all members of the structure. Let me know if you guys can see anything wrong:

// Declaring the structure:

typedef struct stEntry{
	char *lexeme;
	int line;
	int idcount;
	} SYMBOLTABLEENTRY;

// Creating the array of structures:

SYMBOLTABLEENTRY *symbolTable[200];

// The function to create a new struct for the array

SYMBOLTABLEENTRY *createEntry(char* yytext, int ln, int id)
{	
	SYMBOLTABLEENTRY *temp_st;
	temp_st = (SYMBOLTABLEENTRY *)malloc(sizeof(SYMBOLTABLEENTRY));
	temp_st->lexeme = strcpy(test, yytext);
	temp_st->line = ln;
	temp_st->idcount = id;
	return temp_st;
}

// When it finds an ID token, it adds a struct to the array

{ID} {printf("found ID token"); symbolTable[tol++] = createEntry(yytext, lineno, idcount++);}

// Where I'm having the problems, trying to print all elements of the struct array:

void printEntries()
   {
		for(i = 0; i < tol; i++)
		{
			sprintf(symbolTable[i].line,"%d:");
			printf("", symbolTable[i].lexeme);
			printf("(", symbolTable[i].idcount, ")\n");
		}
   }

[blernblan]

I posted the code in segments to make it easier to follow, but here's the entire file:

%option noyywrap

%{

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
int count = 0;
int lineno = 1;
int idcount = 0;
int tol = 0;
char* test;
int i, j;

typedef struct stEntry{
	char *lexeme;
	int line;
	int idcount;
	} SYMBOLTABLEENTRY;
	
SYMBOLTABLEENTRY *symbolTable[200];

// Create the symbol table entry and return a pointer to that table
SYMBOLTABLEENTRY *createEntry(char* yytext, int ln, int id)
{	
	SYMBOLTABLEENTRY *temp_st;
	temp_st = (SYMBOLTABLEENTRY *)malloc(sizeof(SYMBOLTABLEENTRY));
	temp_st->lexeme = strcpy(test, yytext);
	temp_st->line = ln;
	temp_st->idcount = id;
	return temp_st;
}

// Walk symboltable and print entries.  This is a pre-order depth-first walk
/*
void walkTable( SYMBOLTABLE *ts, int level) {
	/* if tp is not null 
	if (ts) {
		// print the indentation for this node
		int i;
		for (i = 0; i < level; i++) 
			printf( "  ");
		// print the label for this node
		printf( "%s\n", ts->lexeme);
		// process my children
		// both children are at the next level down
		level++;
		walkTable( ts->line, level);
		//walkTable( st->position, level);
	}
	// tp was null, so don't try to do anything.
	return;
}*/

%}

plus "+"
min "-"
times "*"
divide "/"
rbrace "}"
lbrace "{"
lparen "("
rparen ")"
lbrack "["
rbrack "]"
assign "="
eq "=="
noteq "!="
gt ">"
lt "<"
gtoreq ">="
ltoreq "<="
semi ";"
col ":"
com ","
wspc \t
wspcs " "


%x comment
digit [0-9]
NUM {digit}{digit}*
letter [a-zA-Z]
ID {letter}{letter}*
newline \n
if "if"
while "while"
for "for"
else "else"
int "int"
void "void"
return "return"

%%
"/*"         BEGIN(comment);

<comment>[^*\n]*        /* eat anything that's not a '*' */
<comment>"*"+[^*/\n]*   /* eat up '*'s not followed by '/'s */
<comment>\n             printf("%d:\n", lineno++);
<comment>"*"+"/"        BEGIN(INITIAL); 
<comment><<EOF>>		printf("error: EOF in comment."); yyterminate();


{newline} {printf("%d:\n", lineno++); idcount = 0;}
{if} {printf("found IF token.\n");}
{else} {printf("found ELSE token.\n");}
{while} {printf("found WHILE token.\n");}
{for} {printf("found FOR token.\n");}
{void} {printf("found VOID token.\n");}
{int} {printf("found INT token.\n");}
{semi} {printf("found SEMI token.\n");}
{col} {printf("found COL token.\n");}
{assign} {printf("found ASSIGN token.\n");}
{return} {printf("found RETURN token.\n");}


{plus} {printf("found PLUS token.\n");}   
{min} {printf("found MINUS token.\n");}
{times} {printf("found TIMES token.\n");}
{divide} {printf("found OVER token.\n");}
{rbrace} {printf("found RBRACE token.\n");}
{lbrace} {printf("found LBRACE token.\n");}
{rparen} {printf("found RPAREN token.\n");}
{lparen} {printf("found LPAREN token.\n");}
{rbrack} {printf("found RBRACKET token.\n");}
{lbrack} {printf("found LBRACKET token.\n");}
{eq} {printf("found EQUALS token.\n");}
{noteq} {printf("found NEQ token.\n");}
{gt} {printf("found GT token.\n");}
{lt} {printf("found LT token.\n");}
{gtoreq} {printf("found GTEQ token.\n");}
{ltoreq} {printf("found LTEQ token.\n");}
{com} {printf("found COMMA token.\n");}
{NUM} {printf("found NUM token.\n");}
{wspc} {printf("");}
{wspcs} {printf("");}
{ID} {printf("found ID token"); symbolTable[tol++] = createEntry(yytext, lineno, idcount++);}
%%

int main()
{
   printf("%d:\n", lineno++);
   yylex();
   
   void printEntries()
   {
		for(i = 0; i < tol; i++)
		{
			sprintf(symbolTable[i].line,"%d:");
			printf("", symbolTable[i].lexeme);
			printf("(", symbolTable[i].idcount, ")\n");
		}
   }
   
   return 0;
}

[hk_mp5kpdw]

// Where I'm having the problems, trying to print all elements of the struct array:

void printEntries()
   {
		for(i = 0; i < tol; i++)
		{
			sprintf(symbolTable[i].line,"%d:");
			printf("", symbolTable[i].lexeme);
			printf("(", symbolTable[i].idcount, ")\n");
		}
   }

symbolTable[i] is a pointer to a struct, not a struct by itself. You need to use -> and not the dot operator to access the members.

Also, this looks questionable:

char* test;

...

typedef struct stEntry{
	char *lexeme;
	int line;
	int idcount;
	} SYMBOLTABLEENTRY;
	
...

SYMBOLTABLEENTRY *createEntry(char* yytext, int ln, int id)
{	
	SYMBOLTABLEENTRY *temp_st;
	temp_st = (SYMBOLTABLEENTRY *)malloc(sizeof(SYMBOLTABLEENTRY));
	temp_st->lexeme = strcpy(test, yytext);
	temp_st->line = ln;
	temp_st->idcount = id;
	return temp_st;
}

[blernblan]

Alright I got the thing to compile by changing the print function as follows:

void printEntries()
   {
		for(i = 0; i < tol; i++)
		{
			printf("%d", symbolTable[i]->line, ":");
			printf("%s", symbolTable[i]->lexeme);
			printf("( %d", symbolTable[i]->idcount, ")\n");
		}
   }

But now I'm getting the following error when I try to run the .exe:


3 [main] lab3 169968_cygtls::handle_exceptions: Error while dumping state <probably corrupted stack>
Segmentation fault <core dumped>

Anyone know what this means?

[quzah]

Your last line is wrong. You make one string, with all of the conversion specifiers in it, and follow it with all the conversion variables.

printf( "( %d )\n", symbolTable[i]->idcount );

You should start by printing out tol before you start using it in the loop, to see if it's what you expect it to be.

Also, be more descriptive. What's the last thing it does before it throws a runtime error? Start looking there.


Quzah.