Greenhand want help!

Hi Experts,

I'm greenhand to C, please lend me a hand why I can not get following Source compiled correctly?


Thanks in advance!

Rick


#include <stdio.h>

#define FALSE 0
#define NULL 0

typedef struct {
int dataitem;
struct listelement *link;
} listelement;

void Menu (int *choice);
listelement * AddItem (listelement * listpointer, int data);
listelement * RemoveItem (listelement * listpointer);
void PrintQueue (listelement * listpointer);
void ClearQueue (listelement * listpointer);

main () {
listelement listmember, *listpointer;
int data,
choice;

listpointer = NULL;
do {
Menu (&choice);
switch (choice) {
case 1:
printf ("Enter data item value to add ");
scanf ("%d", &data);
listpointer = AddItem (listpointer, data);
break;
case 2:
if (listpointer == NULL)
printf ("Queue empty!\n");
else
listpointer = RemoveItem (listpointer);
break;
case 3:
PrintQueue (listpointer);
break;

case 4:
break;

default:
printf ("Invalid menu choice - try again\n");
break;
}
} while (choice != 4);
ClearQueue (listpointer);
} /* main */

void Menu (int *choice) {

char local;

printf ("\nEnter\t1 to add item,\n\t2 to remove item\n\
\t3 to print queue\n\t4 to quit\n");
do {
local = getchar ();
if ((isdigit (local) == FALSE) && (local != '\n')) {
printf ("\nyou must enter an integer.\n");
printf ("Enter 1 to add, 2 to remove, 3 to print, 4 to quit\n");
}
} while (isdigit ((unsigned char) local) == FALSE);
*choice = (int) local - '0';
}

listelement * AddItem (listelement * listpointer, int data) {

listelement * lp = listpointer;

if (listpointer != NULL) {
while (listpointer -> link != NULL)
listpointer = listpointer -> link;
listpointer -> link = (struct listelement *) malloc (sizeof (listelement));
listpointer = listpointer -> link;
listpointer -> link = NULL;
listpointer -> dataitem = data;
return lp;
}
else {
listpointer = (struct listelement *) malloc (sizeof (listelement));
listpointer -> link = NULL;
listpointer -> dataitem = data;
return listpointer;
}
}

listelement * RemoveItem (listelement * listpointer) {

listelement * tempp;
printf ("Element removed is %d\n", listpointer -> dataitem);
tempp = listpointer -> link;
free (listpointer);
return tempp;
}

void PrintQueue (listelement * listpointer) {

if (listpointer == NULL)
printf ("queue is empty!\n");
else
while (listpointer != NULL) {
printf ("%d\t", listpointer -> dataitem);
listpointer = listpointer -> link;
}
printf ("\n");
}

void ClearQueue (listelement * listpointer) {

while (listpointer != NULL) {
listpointer = RemoveItem (listpointer);
}
}

Well, what errors do you get? This is one thing that I found:

Code:

---


typedef struct
{
  int dataitem;
  struct listelement *link;
}listelement;

I believe this one should be:

typedef struct listelement
{
  int dataitem;
  listelement *link;
}listelement;


---

main() should be int main(). I don't know if your compiler automatically makes this if there are no void in front of it...

- You need to add some include files:

#include <ctype.h> /* needed for isdigit */
#include <stdlib.h> /* needed for malloc, free */
#include <malloc.h> /* needed ? for malloc, free */

- Also remove the listmember in main()

listelement *listpointer;

Now the code is:

#include <stdio.h>
#include <ctype.h>
#include <stdlib.h>
#include <malloc.h>

#define FALSE 0
#define NULL 0

typedef struct listelement
{
int dataitem;
listelement *link;
}listelement;

void Menu(int *choice);
listelement *AddItem(listelement *listpointer,int data);
listelement *RemoveItem(listelement *listpointer);
void PrintQueue(listelement *listpointer);
void ClearQueue(listelement *listpointer);
void main(){
listelement listmember,*listpointer;
int data;
int choice;

listpointer = NULL;
do{
Menu(&choice);
switch(choice){
case 1:
printf("Enter data item value to add ");
scanf("%d",&data);
listpointer = AddItem(listpointer,data);
break;
case 2:
if(listpointer == NULL)
printf("Queue empty!\n");
else
listpointer = RemoveItem(listpointer);
break;
case 3:
PrintQueue(listpointer);
break;
case 4:
break;
default:
printf("Invalid menu choice-try again\n");
break;
}
}while(choice! = 4);
ClearQueue(listpointer);
} /*main*/
void Menu(int *choice){

char local;

printf("\nEnter\t1 to add item,\n\t2 to remove item\n\t3 to print queue\
n\t4 to quit\n");
do{
local = getchar();
if((isdigit(local) == FALSE)&&(local != '\n')){
printf("\nyou must enter an integer.\n");
printf("Enter 1 to add, 2 to remove, 3 to print,
4 to quit\n");
}
}while(isdigit((unsigned char)local) == FALSE);
*choice = (int)local-'0';
}

listelement *AddItem(listelement *listpointer,int data){
listelement *lp = listpointer;

if(listpointer!=NULL){
while(listpointer -> link != NULL)
listpointer = listpointer -> link;
listpointer -> link = (struct listelement *)malloc(sizeof(listel
ement));
listpointer = listpointer -> link;
listpointer -> link = NULL;
listpointer -> dataitem = data;
return lp;
}
else {
listpointer = (struct listelement *)malloc(sizeof(listelement));
listpointer -> link = NULL;
listpointer -> dataitem = data;
return listpointer;
}
}

listelement *RemoveItem(listelement *listpointer){

listelement *tempp;
printf("Element removed is %d\n",listpointer -> dataitem);
tempp = listpointer -> link;
free(listpointer);
return termpp;
}

void PrintQueue(listpointer *listpointer){

if(listpointer == NULL)
printf("queue is empty!\n")'
else
while(listpointer != NULL){
printf("%d\t",listpointer -> dataitem);
listpointer = listpointer -> link;
}
printf("\n");
}
}

void ClearQueue(listelement *listpointer){

while(listpointer != NULL){
listpointer = RemoveItem(listpointer);
}
}

--------------- CUT HERE ---------------------------------------

And I use "lint" to the file, the output is:


lint: "queue.c", line 16: error 1000: Unexpected symbol: "listelement".
lint: "queue.c", line 20: error 1000: Unexpected symbol: "*".
lint: "queue.c", line 21: error 1000: Unexpected symbol: "*".
lint: "queue.c", line 21: error 1000: Unexpected symbol: ";".
lint: "queue.c", line 22: error 1000: Unexpected symbol: ";".
lint: "queue.c", line 23: error 1000: Unexpected symbol: ";".
lint: "queue.c", line 19: error 1705: Function prototypes are an ANSI feature.
lint: "queue.c", line 20: error 1705: Function prototypes are an ANSI feature.
lint: "queue.c", line 20: error 1573: Type of "listpointer" is undefined due to
an illegal declaration.
lint: "queue.c", line 25: warning 845: errors seen skipping the code including f
unction.
lint: "queue.c", line 26: error 1000: Unexpected symbol: "listmember".
lint: "queue.c", line 54: error 1000: Unexpected symbol: "!".
lint: "queue.c", line 23: warning 558: Empty declaration.
lint: "queue.c", line 26: error 1573: Type of "listmember" is undefined due to a
n illegal declaration.
lint: "queue.c", line 26: error 1573: Type of "listpointer" is undefined due to
an illegal declaration.
lint: "queue.c", line 30: error 1549: Modifiable lvalue required for assignment
operator.
lint: "queue.c", line 37: warning 563: Argument #1 is not the correct type.
lint: "queue.c", line 37: warning 563: Argument #2 is not the correct type.
lint: "queue.c", line 37: error 1549: Modifiable lvalue required for assignment
operator.
lint: "queue.c", line 40: error 1563: Expression in if must be scalar.
lint: "queue.c", line 43: error 1549: Modifiable lvalue required for assignment
operator.
lint: "queue.c", line 25: warning 845: errors seen skipping the code including f
unction.
lint: "queue.c", line 57: error 1705: Function prototypes are an ANSI feature.
lint: "queue.c", line 57: warning 845: errors seen skipping the code including f
unction.
lint: "queue.c", line 72: error 1000: Unexpected symbol: "*".
lint: "queue.c", line 72: error 1000: Unexpected symbol: "int".
lint: "queue.c", line 72: error 1000: Unexpected symbol: "{".
lint: "queue.c", line 72: warning 845: errors seen skipping the code including f
unction.
lint: "queue.c", line 75: error 1000: Unexpected symbol: "if".
lint: "queue.c", line 75: error 1000: Unexpected symbol: "!=".
lint: "queue.c", line 75: error 1000: Unexpected symbol: "{".
lint: "queue.c", line 76: error 1000: Unexpected symbol: "->".
lint: "queue.c", line 76: error 1000: Unexpected symbol: "!=".
lint: "queue.c", line 77: error 1000: Unexpected symbol: "listpointer".
lint: "queue.c", line 78: error 1000: Unexpected symbol: "->".
lint: "queue.c", line 80: error 1000: Unexpected symbol: "->".
lint: "queue.c", line 81: error 1000: Unexpected symbol: "->".
lint: "queue.c", line 82: error 1000: Unexpected symbol: "return".
lint: "queue.c", line 83: error 1000: Unexpected symbol: "}".
lint: "queue.c", line 86: error 1000: Unexpected symbol: "->".
lint: "queue.c", line 87: error 1000: Unexpected symbol: "->".
lint: "queue.c", line 88: error 1000: Unexpected symbol: "return".
lint: "queue.c", line 89: error 1000: Unexpected symbol: "}".
lint: "queue.c", line 92: error 1000: Unexpected symbol: "{".
lint: "queue.c", line 73: warning 557: Missing declaration specifiers, "int" ass
umed.
lint: "queue.c", line 73: error 1588: "listpointer" undefined.
lint: "queue.c", line 73: error 1521: Incorrect initialization.
lint: "queue.c", line 75: error 1506: Parameters allowed in function definition
only.
lint: "queue.c", line 75: error 1584: Inconsistent type declaration: "listpointe
r".
lint: error 2017: Cannot recover from earlier errors, terminating.


------------------------------------------- CUT HERE ---------------------------


You see, too many errors!!!

Most of them are simply syntax errors which can easily be fixed.

The code is a little bit messy. Plz use the code tag ( [ C O D E ] ... [ / C O D E ] ) to make it look better next time, like this:

Code:

---

int main()
{
  printf("Hello");
  getch();
  return 0;
}

---

"Unexpected symbol"? Hmm, I have never got that error before... Must be some syntax error somewhere!

This looks a bit dubious...

>>>
typedef struct listelement
{
int dataitem;
listelement *link;
}listelement;
<<<

... you are declaring a type, and an object of that type, with the same name. Is that really what you want to do? Later, you are creating objects and pointers to them, I think you may be better off with this...

>>>
typedef struct listelement
{
int dataitem;
listelement *link;
};
<<<