int varriable print to file

Hello,
New problem.

maybe it's stupid but I'm stuck.

I want to write a long int varriable into a file, do I need to transform it to binary take the lower 8 bits and using fputc print and remove them
every time for the entire number? or is there a better way?

I've searched the board but all I find are functions to print chars,
strings and arrays when what I need is a simple int var. :(

You can use fprintf to print to a file.

Code:

---

FILE *infile = fopen(FileName, "w");
fprintf(infile, "%l", LongVar);
fclose(infile);

---

- Sean

>fprintf(infile, "%l", LongVar);
%l isn't a format specifier for the printf family, I think you meant %ld.

-Prelude

I wrote part of a bigger program and it has a few problems:

1. double prints the menu.

2. where the user has to print y to continue it prints the Q but
automaticaly continues.

I don't know why.

Code:

---

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

void New_Item(int);

void main(){
        char date[9];
        FILE *it;
        FILE *his;
        char choice;
        char user_name[20];
       
        printf("please enter user name\n");
        scanf("%s",&user_name);
        printf("please enter date\n");
        scanf("%s",&date);
               
        while(choice!='9')
        {
                printf("please enter an option\n");
                printf("%d to enter new item\n",1);
                printf("%d to delete item\n",2);
                printf("%d to add to stock\n",3);
                printf("%d to remove from stock\n",4);
                printf("%d to update comments\n",5);
                printf("%d to item inquire\n",6);
                printf("%d for report\n",7);
                printf("%d to end\n",8);
                printf("%d to logout\n",9);
                scanf("%c",&choice);
                switch(choice){

                case '1':
                        New_Item(1);
                        break;
                }
        }
}

void New_Item(int){
char ans;
long int itemid=0,qntty=0;
char date[9],item_name[20],comm[40];
FILE *it;
        if((it=fopen("Items","r+"))==NULL)
        {
                printf("you want to start a new file\n");
                printf("y or n\n");
                scanf("%c",&ans);
                if(ans=='n' || ans=='N')
                        return;
        }
       
        for( ; ; )
        {
                printf("enter item's id, max 999999999\n");
                if(scanf("%ld",itemid)==1)
                {
                        if(itemid>0 && itemid<=999999999)
                        {
                                printf("enter item's name max %d chars\n",20);
                                fgets(item_name,20,stdin);
                                printf("enter item's quantity \n");
                       
                                if(scanf("%ld",qntty)==1)
                                {
                                        if(qntty>0 && qntty<=1000000)
                                        {
                                                printf("enter comments\n");
                                                fgets(comm,40,stdin);
                                        }
                                        else
                                        {
                                                printf("item's quantity is out of range\n");
                                                printf("quantity can be between %d and %d\n",1,1000000);
                                        }
                                }
                                else
                                        printf("that was not a number\n");
                        }
                        else
                        {
                                printf("item's id is out of range\n");
                                printf("id can be between %d and %d\n",1,999999999);
                        }
                }
                else
                        printf("that was not a number\n");
                while(getchar()!='\n');
        }

        fprintf(it,"%ld ",itemid);
        fputs(item_name,it);
        fputc(' ',it);
        fprintf(it,"%ld ",qntty);
        fputs(comm,it);
        fclose(it);
}

---

First spot:
>void New_Item(int){
your haven't named the variable.

>Unreachable code.
The for (;;) loop in the New_Item() function never ends, there's no break, return etc.

It double prints the menu because theres a new line character left in the buffer from this scanf()
>scanf("%s", &date);
and when it reaches this scanf()
>scanf("%c", &choice);
the newline is read in again.

>if(scanf("%ld",itemid)==1)
scanf() news a pointer for its second arg. Use &itemid

>printf("quantity can be between %d and %d\n", 1, 1000000);
%d is for int's which are limited in size (as per one of our other conversations). The number 1000000 is too big. Use %ld.

Quote:

---

Originally posted by Hammer
First spot:
>void New_Item(int){
your haven't named the variable.

>Unreachable code.
The for (;;) loop in the New_Item() function never ends, there's no break, return etc.

It double prints the menu because theres a new line character left in the buffer from this scanf()
>scanf("%s", &date);
and when it reaches this scanf()
>scanf("%c", &choice);
the newline is read in again.

---

Is this better?

> for(;getchar()!='\n';)

> void New_Item(int num)

1. the thing is, I'm not using any variable frm "main" I only used it
to call the function. is that o.k?

2. I still don't understand why it double prints the menu.

I'm sorry but I'm still at the begining of c prog.

oops....

forgot to register before.

After this:
>scanf("%s", &date);
put this:
>while (getchar() != '\n');
This will eat up the extra byte from the input buffer.

(and yes, use the while not for version)

Also
>void main(void)
No, use int main(void)

>char choice;
>while (choice != '9')
You didn't initialise choice before you tested it for a specific value. Better to set it to something first. Eg:
>char choice = ' ';

Did you fix your infinite loop?

Quote:

---

Originally posted by Hammer
After this:
>scanf("%s", &date);
put this:
>while (getchar() != '\n');
This will eat up the extra byte from the input buffer.

(and yes, use the while not for version)

Also
>void main(void)
No, use int main(void)

>char choice;
>while (choice != '9')
You didn't initialise choice before you tested it for a specific value. Better to set it to something first. Eg:
>char choice = ' ';

Did you fix your infinite loop?

---

1. my loop now looks like this : "for(;getchar()!='\n'; )".

2. I initialised "choice" and used "while (getchar() != '\n');" after
"scanf("%s", &date);".

now it stoped double printing the menu.

Thank You.
--------------------------------------------------------
I hope you won't mind if I ask another Q?...

When I try to enter the item id no. I get the following error message:

The instruction at "0x00406188" referenced
memory "0x00000000". The memory could not be "written".

What does it mean?

>The instruction at "0x00406188" referenced
>memory "0x00000000". The memory could not be "written".
Do you mean this line:
>if (scanf("%ld", itemid) == 1)
If so, you've forgotten the &. Make it &itemid.

>my loop now looks like this : "for(;getchar()!='\n'; )".
It shouldn't. The outer statement
>for ( ;; )
is correct, this does create an infinite loop, you just need to force a break-out when you get the data you want. (Sorry, maybe I confused you earlier). I'd guess that would be after you've asked for comments:
>fgets(comm, 40, stdin);
So, I'd suggest adding a break; statement after that line (I am presuming that once the user has entered comments, you want to leave the for loop and write the data to the file).

This bit
>while (getchar() != '\n');
is used to clear the input buffer and I believe should be left as the last thing in the for loop. That way, the input buffer is cleared before going back to the top and asking for the itemid again.

If you get stuck, post that function again with you latest changes, an I'll have another look.

Quote:

---

[i]>If you get stuck, post that function again with you latest changes, an I'll have another look.[/B]

---

I did the changes and it just goes crazy.

I think it's best just to post the function.

Hopfully after this I will be able to do the remaining 5 functions
all by myself.
(I thought the algoritems were the hard part. I was sooo wrong.)

By the way we HAVE to use " void main" I know "int main" is better but I'm not a professor yet. ;)

Code:

---

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

void New_Item(int);

void main(){
        char date[9];
        FILE *it;
        FILE *his;
        char choice=' ';
        char user_name[20];
       
        printf("please enter user name\n");
        scanf("%s",&user_name);
        printf("please enter date\n");
        scanf("%s",&date);
        while (getchar() != '\n');
               
        while(choice!='9')
        {
                printf("please enter an option\n");
                printf("%d to enter new item\n",1);
                printf("%d to delete item\n",2);
                printf("%d to add to stock\n",3);
                printf("%d to remove from stock\n",4);
                printf("%d to update comments\n",5);
                printf("%d to item inquire\n",6);
                printf("%d for report\n",7);
                printf("%d to end\n",8);
                printf("%d to logout\n",9);
                scanf("%c",&choice);
       
                switch(choice){

                case '1':
               
                        New_Item(1);

                        break;
                }
        }
}


void New_Item(int num){
char ans;
long int itemid=0,qntty=0;
char date[9],item_name[20],comm[40];
FILE *it;
FILE *his;

        if((it=fopen("Items","r+"))==NULL)
        {
                printf("you want to start a new file\n");
                printf("y or n\n");
                scanf("%c",&ans);
                if(ans=='n' || ans=='N')
                        return;
        }
        for(;;)
        {
                printf("enter item's id, max 999999999\n");
                if(scanf("%ld",&itemid)==1)
                {
                        if(itemid>0 && itemid<=999999999)
                        {
                                printf("enter item's name max %d chars\n",20);
                                fgets(item_name,20,stdin);
                                printf("enter item's quantity \n");
                       
                                if(scanf("%ld",&qntty)==1)
                                {
                                        if(qntty>0 && qntty<=1000000)
                                        {
                                                printf("enter comments\n");
                                                fgets(comm,40,stdin);
                                                break;
                                        }
                                        else
                                        {
                                                printf("item's quantity is out of range\n");
                                                printf("quantity can be between %d and %d\n",1,1000000);
                                        }
                                }
                                else
                                        printf("that was not a number\n");
                        }
                        else
                        {
                                printf("item's id is out of range\n");
                                printf("id can be between %d and %d\n",1,999999999);
                        }
                }
                else
                        printf("that was not a number\n");
                while(getchar()!='\n');
        }

        fprintf(it,"%ld ",itemid);
        fputs(item_name,it);
        fputc(' ',it);
        fprintf(it,"%ld ",qntty);
        fputs(comm,it);
        fclose(it);

        if((his=fopen("history","a"))!=NULL)
        {
                fprintf(his,"%d",itemid);
                fputs(item_name,his);
                fprintf(his,"%d",qntty);
                fclose(his);
        }
}

---

I have added a few bits to your code, see my comments in the source below (watch for "NEW BIT"). You had done alright, it just needed the buffers flushing between each scanf() call.

There is another problem now. The logic for determining if the file "it" is open is flawed. On my PC, I don't have a file called Items, so the fopen() fails
>if ((it = fopen("Items", "r+")) == NULL)
You ask if you want the user to create a new file, and if Y is entered you carry on. But you don't actually open a file in this case. You then proceed through the section getting user data, and then try to write out to an unopened file pointer. If I create the file first, then the fopen() works OK,and there progs writes out correctly.

I'll leave that one for you to sort out for now :)

Code:

---

void New_Item(int num)
{
        /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
        char                ans;
        long int        itemid = 0, qntty = 0;
        char                date[9], item_name[20], comm[40];
        FILE                *it;
        FILE                *his;
        /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/

        if ((it = fopen("Items", "r+")) == NULL)
        {
                printf("you want to start a new file\n");
                printf("y or n\n");
                scanf("%c", &ans);
                if (ans == 'n' || ans == 'N') return;
                while (getchar() != '\n'); /* NEW BIT */
        }

        for (;;)
        {
                printf("enter item's id, max 999999999\n");
                if (scanf("%ld", &itemid) == 1)
                {
                        while (getchar() != '\n'); /* NEW BIT */
                        if (itemid > 0 && itemid <= 999999999)
                        {
                                printf("enter item's name max %d chars\n", 20);
                                fgets(item_name, 20, stdin);
                                printf("enter item's quantity \n");
                                if (scanf("%ld", &qntty) == 1)
                                {
                                        while (getchar() != '\n'); /* NEW BIT */
                                        if (qntty > 0 && qntty <= 1000000)
                                        {
                                                printf("enter comments\n");
                                                fgets(comm, 40, stdin);
                                                break;
                                        }
                                        else
                                        {
                                                printf("item's quantity is out of range\n");
                                                printf("quantity can be between %d and %d\n", 1, 1000000);
                                        }
                                }
                                else
                                        printf("that was not a number\n");
                        }
                        else
                        {
                                printf("item's id is out of range\n");
                                printf("id can be between %d and %d\n", 1, 999999999);
                        }
                }
                else
                        printf("that was not a number\n");
                while (getchar() != '\n');
        }

        fprintf(it, "%ld ", itemid);
        fputs(item_name, it);
        fputc(' ', it);
        fprintf(it, "%ld ", qntty);
        fputs(comm, it);
        fclose(it);
        if ((his = fopen("history", "a")) != NULL)
        {
                fprintf(his, "%d", itemid);
                fputs(item_name, his);
                fprintf(his, "%d", qntty);
                fclose(his);
        }
}

---

sorry it took me so long to reply.
I don't have a compiler at home.

Thank u for the help, Hammer.

I have attached my more extended program.
I'm having a problem. it doesn't accept my 2nd case.

help would be appreciated.