declaring class variable c++ [closed] - c++

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Closed 10 years ago.
So I'm at a complete loss...
In my code I've got
void Parser(FILE* file)
{
Parser par(file);
par.Parse();
}
and I call it in my main function with
Parser(file);
and the header file I've got (which I included in the main file) looks like:
class Parser: public Lexer
{
public:
Parser(FILE* file):Lexer(file);
int Parse();
};
and the error I'm getting is:
p02.cpp: In function 'void Parser(FILE*)':
p02.cpp:20: error: expected ';' before 'par'
p02.cpp:21: error: 'par' was not declared in this scope
make: *** [p02.o] Error 1
What I don't understand is why it is expecting a semicolon before par. Isn't that a legal declaration of a variable for that class?
Edit2: Changing my function name to not be Parser like the class name does not solve this problem. It does give me an extra error telling me that Parser is not declared in this scope, but I cannot see how that is when I've added the include file containing the Parser class right above the declaration for the function.
Edit: My Files
p02.cpp:
#include <stdio.h>
#include <stdlib.h>
#include <iostream>
#include <cstring>
#include <string>
#include "p02lex.h"
#include "y.tab.h"
using namespace std;
void Parser(FILE* file)
{
Parser par(file);
par.Parse();
}
int main(int argc, char* argv[])
{
char fileName[255];
switch(argc)
{
case 1:
cout << "Enter the input file name. ";
cin >> fileName;
break;
case 2:
strcpy(fileName, argv[1]);
break;
default:
cout << "Too many arguments!\n";
exit(1);
}
FILE* file = fopen(fileName, "r");
Parser(file);
fclose(file);
return 0;
}
p02lex.l:
#include "p02lex.h"
#define ID 257
...
#define PROGRAM 304
int TokenMgr(int t);
const char* getTokens(int tokenCode);
unsigned lineCount = 1, columnCount = 1;
%}
LETTER [a-z]|[A-Z]
DIGIT [0-9]
%%
// rules defined here, calling TokenMgr()
%%
int TokenMgr(int t)
{
/* int tc = t;
if (t == IDENTIFIER)
{
char s[1024];
ToLower(s, yytext, strlen(yytext));
tc = RW[s];
if (tc == 0)
tc = t;
}
PrintToken(tfs, tc, line, col);
col += yyleng; */ //JEG
printf("Token:Code=%d Name=%10s line=%3u col=%3u Spelling=\"%s\"\n", t, getTokens(t), lineCount, columnCount, yytext);
columnCount += yyleng;
return /* tc */ 0; // JEG
}
Lexer::Lexer(FILE* file)
{
yyin = file;
}
int Lexer::Scan(void)
{
return yylex();
}
const char* getTokens(int tokenCode)
{
switch(tokenCode)
{
case ID:
return "ID";
... // more cases, returning strings
default:
return NULL;
}
}
p02lex.h:
#ifndef p02lex_h
#define p02lex_h 1
#endif
int yylex(void);
class Lexer
{
public:
Lexer(FILE* file);
int Scan(void);
};
p02par.h:
#ifndef p02par_h
#define p02par_h 1
#endif
using namespace std;
#ifdef __cplusplus
extern "C"
#endif
int yyparse(void);
class Parser: public Lexer
{
public:
Parser(FILE* file):Lexer(file){}
void Parse();
// int Scan(void);
};
p02par.y:
#include <stdio.h>
#include "p02lex.h"
#include "p02par.h"
void yyerror(const char* m);
%}
%token PROGRAM
%token ID
%token SEMICOLON
%%
program:
PROGRAM ID SEMICOLON
{ printf("Stuff happens!\n"); }
%%
void yyerror(const char* m)
{
printf("%s\n", m);
}
/*Parser::Parser(FILE* file):Lexer(file)
{
}*/
int Parser::Parse()
{
return yyparse();
}
p02make:
#LEX = flex
#YACC = yacc -d
CC = g++
OBJ = p02.o p02par.o p02lex.o
p02: ${OBJ}
$(CC) -o p02 ${OBJ} -ll -ly
y.tab.h p02par.cpp: p02par.y
yacc -d -v p02par.y
mv y.tab.c p02par.cpp
p02lex.cpp: p02lex.l
lex p02lex.l
mv lex.yy.c p02lex.cpp
p02par.o: p02par.cpp p02par.h
$(CC) -c -g p02par.cpp
p02.o: p02.cpp p02lex.h p02par.h
$(CC) -c -g p02.cpp
p02lex.o: p02lex.cpp p02lex.h y.tab.h
$(CC) -c -g p02lex.cpp

Answer 1

that should be :
Parser(File* file):Lexer(file) {}
Wait I checked that code, rename the function: void Parser(FILE *f) to something else.

Answer 2

You can only include an initializer list in a constructor definition, not a constructor declaration, so it must be followed by a function body (often empty), not a semicolon. There's also a bit of a problem with a name conflict:
void Parser(FILE* file) // here you've defined Parser as the name of a function
{
Parser par(file); // but here you're trying to use it as the name of a class.
par.Parse();
}
Edit: Here's a bit of code that compiles cleanly, at least with the compilers I have handy:
#include <stdio.h>
class Lexer {
FILE *infile;
public:
Lexer(FILE *f) : infile(f) {}
};
class Parser : public Lexer {
public:
Parser(FILE *f) : Lexer(f) {}
void Parse() {}
};
void do_parse(FILE *file) {
Parser p(file);
p.Parse();
}

Answer 3

You need to qualify Parser because the function has the same identifier as the class:
void Parser(FILE* file)
{
class Parser par(file);
par.Parse();
}
You could also rename the function.
You also need braces here:
Parser(FILE* file):Lexer(file) {}

Answer 4

Change
void Parser(FILE* file)
to
Parser::Parser(FILE* file)
Constructors do not have a return type.