C structures

exvor · 03-03-2006, 11:41 AM

Im having a rather odd error and wondering if im trying to do something illegal.

I have a very simple program that defines 2 structures and then inputs code into each one. I dont get an error with the first one but i do when i use the structure definition again.

here is a snippet of what it looks like.

Code:


typedef struct {
   char text[5]; 
   char t; 
   } stuff; 


int main()
{ 

   stuff one; 
   <<adds some data to the structure elements>> 
  
   stuff two; 
   <<adds some data like the first one>> 


return 0 
}

when i attempt to compile i get error "Improper use of a typedef symbol in function main"

So is this allowed or do i need to allocate memory first with a malloc command to get it to work. Or am i just crazy and this is wrong ?

bigearsbilly · 03-03-2006, 11:47 AM

semicolon on return

paulsm4 · 03-03-2006, 11:51 AM

You didn't post the error message, but I suspect the (at least one) problem might be with your "typedef", and would go away if you did this:

Code:

struct stuff
{
  char text[5]; 
  char t; 
} 
  stuff; 

int 
main(int argc, char *argv[])
{ 

   struct stuff one; 
   <<adds some data to the structure elements>> 
  
   struct stuff two; 
   <<adds some data like the first one>> 

  return 0; 
}/

This link might explain a bit better:
http://www.embedded.com/showArticle....icleID=9900748

'Hope that helps .. PSM

PS:
Personally, I generally prefer to leave "struct's" as "struct" instead of making a typedef. I definitely encourage you to give the return value and arguments for "main()", even if you don't use them.

PPS:
No, if you declare the struct as a variable, then you don't need to call "malloc()".

exvor · 03-03-2006, 12:00 PM

On the original code it has one thats just a typeing error when i retyped it.

So its not whats causing the problem.

let me post the original code here

Code:

 
#include<stdio.h>


int main()
{

  typedef struct{
   char text[5];
   int t;
   } stuff;

  char hold[5];


  stuff tag;
  sprintf(tag.text,"help");
  tag.t=5;

  stuff bete;
  printf("%s","Please enter a word no more then 4 letters.\n");

  scanf("%s",hold);
  sscanf(hold,"%s",bete.text);
  printf("%s","Please enter a number.\n");

  scanf("%s",hold);
  sscanf(hold,"%d",bete.t);


  printf("info is %s %d\n",tag.text,tag.t);

  printf("you typed %s %d\n",bete.text,bete.t);

  return 0;
}

mic · 03-03-2006, 12:04 PM

Now that's different from your 1st post
Move this:

Code:

typedef struct{
   char text[5];
   int t;
   } stuff;

before main() and it should work.

Also, declare all local vars at the beggining of function. This is not required but increases readability and is common practice.

mic · 03-03-2006, 12:14 PM

Funny, I tried your code and it compiles fine. Anyway, I've never seen somebody define a struct inside a function. Usually you put that in header file or at least before function definitions.

Also, correct this:

Code:

sscanf(hold,"%d",bete.t);

to

Code:

sscanf(hold,"%d",&bete.t);

You need to pass the address if you want the function to change a primitive (not array or struct, etc) variable.

exvor · 03-03-2006, 12:23 PM

Mic ive done that and get the same error.

PSM

i do have a return statement just forgot the ; when I typed it.

I personally wouldent use a typedef on a structure but im just refreshing my currenly learned skilles. I havent touched programming in about a month and i dont wanna forget stuff. but this error is perplexing.

Im wondering if this is due to the old compiler im trying.

exvor · 03-03-2006, 12:30 PM

Quote:

Originally Posted by mic

Funny, I tried your code and it compiles fine. Anyway, I've never seen somebody define a struct inside a function. Usually you put that in header file or at least before function definitions.

Yea im thinking its the age of the compiler im using. As for my structure definiton i have a talent for doing wierd crap

Quote:

Originally Posted by mic

You need to pass the address if you want the function to change a primitive (not array or struct, etc) variable.

Yea my bad I knew i forgot something with that statement

paulsm4 · 03-04-2006, 12:41 AM

If you didn't have the "typedef", you could declare and define the struct wherever you want (inside or outside the function), in any combination (separately, or all at once) you want ;-)