Subject:	Re: Need help with c!
Approved:	clc AT plethora DOT net
References:	<clcm-19990117-0010 AT plethora DOT net>
From:	"Marp" <Marp AT 0 DOT 0 DOT 0 DOT 0>
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Message-ID:	<clcm-19990123-0009@plethora.net>
Originator:	clcm AT plethora DOT net (Comp Lang C'Moderated)
Date:	Sun, 24 Jan 1999 04:37:25 GMT
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To:	djgpp AT delorie DOT com
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Reply-To:	djgpp AT delorie DOT com

Get rid of the word static in front of FILE *fptr because that should be
able to change as you work with the file. If it can't change it won't work
properly.

Mohanaraj Gopala Krishnan wrote in message ...
>Hi,
>
>I use djgpp and am kinda new to c. I am not sure if this is the right
>group to post this but I am very much hoping I can get help here. I have
>this source code which has no problem when compiling and producing the
>exe. But if i trace through it there is a particular function which is
>problematic. The function is as follows, it a file reading function...
>
>#include <stdio.h>
>#include <stdlib.h>
>
>static FILE *fptr;
>static int recsize;
>
>void open_file(int * pages_done, int array_size);
>void close_file(int * pages_done, int array_size);
>void write_file(char * strpointer, int page_size, int page_no);
>
>void open_file(int * pages_done, int array_size)
>{
>        int i=0;
>
>        if((fptr=fopen("chapter.dat", "r")) !=NULL) {
>
>fseek(fptr,0L,SEEK_SET);
>
>for(i=0;i<array_size;i++) {
>
>fscanf(fptr,"%d",*(pages_done++));
>
>}
>                                                      }
>        else if((fptr=fopen("chapter.dat","w+b")) !=NULL) {
>
>fseek(fptr,0L,SEEK_SET);
>
>for(i=0;i<array_size;i++) {
>
>fprintf(fptr,"%d",*(pages_done++));
>
>}
>                                                          }
>        else {
>             printf("Cannot open or start new chapter!!!");
>             exit(1);
>             }
>}
>
>The problem is with the first open and read only line. If there is no
>chapter.dat file in the program it is okay, but once the chapter.dat
>file already exists, the program quits straight away. The function
>receives two arguments, one a pointer which directs to an array of 100
>digits initialied in a different function. This array is actual;ly the
>management info of the file. The rest of the file is structures. Just in
>case it is hard to follow i have included all the major source code as
>follows. The only thing not here is the input function which is really
>just a custom input function :) Sorry if things are cluttered.
>
>Thank you so much.
>
>THIS IS THE FILE--IT CONTAINS THE MENU AND STUFF
>
>/* GENERAL COMMENTS:1.must customize input with esc as exit */
>/*2.must add continue+new together, asks for file, if none new, if not
>continue :) */
>/*3.must add the clear screen function*/
>
>#include <stdio.h>
>
>
>void menu(void);
>
>void printmenu(void);
>
>void FUNCT_new_page(void);
>
>void
>
>main()
>{
>
>
>       /*PAGE output_page;*/
>
>       menu();
>
>
>
>       /*read_page((char *)&output_page);
>       display_page(output_page);*/
>
>       return 0;
>}
>
>void menu(void)
>{
>        char choice;
>        int done=0;
>
>        do {
>           printmenu();
>           choice=getch();
>
>           switch(choice) {
>                          case 'n':
>                               FUNCT_new_page();
>                               break;
>
>                          case 'c':
>                               printf("This will continue the editing of
>an existing chapter");
>                               break;
>
>                          case 'p':
>                               printf("This will play a chapter");
>                               break;
>
>                          case 'q':
>                               printf("This will quit this menu");
>                               done=1;
>                               break;
>
>                          default:
>                               break;
>                          }
>           }while(!done);
>}
>
>void printmenu(void)
>{
>        printf("a saradiya solutions product\n\n\n");
>        printf("\t n--start new chapter\n");
>        printf("\t c--continue editing existing chapter\n");
>        printf("\t p--play a chapter file\n");
>        printf("\t q--quit this thing");
>        printf("\n\n");
>        printf("\t enter yer choice ");
>}
>
>THIS IS THE SOURCE WHICH DEALS WITH THE PAGE CHARACTERISTICS AND
>FUNCTIONS
>
>#include <stdio.h>
>
>#define STORY_LENGTH 300
>#define OPTION_1_LENGTH 50
>#define OPTION_2_LENGTH 50
>#define MAN_ARRAY_SIZE 100
>
>typedef struct page {
>        int no;
>        char option_1[OPTION_1_LENGTH];
>        int link_1;
>        char option_2[OPTION_2_LENGTH];
>        int link_2;
>        char story[STORY_LENGTH];
>        } PAGE;
>
>
>/*will accept page number next also include the size of the structure*/
>/*void read_page(char* strpointer);*/
>
>/*will return link choice next time*/
>/*void display_page(PAGE VAR_page_displaying);
>
>/*this function receives nothinbg it just fills up a structure and
>returns it*/
>/*PAGE input_page(void); */
>
>/*2nd level implementation */
>void FUNCT_new_page(void);
>
>/*file access stuff in file.c*/
>void open_file(int * pages_done, int array_size);
>void close_file(int * pages_done, int array_size);
>void write_file(char * strpointer, int page_size, int page_no);
>
>/*page stuffin here */
>void display_page(PAGE VAR_page_displaying);
>PAGE input_page(void);
>
>void read_page(char * strpointer)
>{
>        FILE *page_write;
>        PAGE page;
>
>        page_write=fopen("chapter.dat","r");
>        if(page_write==NULL)
>        {
>                puts("No chapter found!!");
>                return;
>        }
>
>        fread(strpointer,sizeof(page),1,page_write);
>}
>
>void display_page(PAGE VAR_page_displaying)
>{
>        printf("Page number: %d\n\n",VAR_page_displaying.no);
>        printf("Text: %s\n\n",VAR_page_displaying.story);
>        printf("%s press 1\n",VAR_page_displaying.option_1);
>        printf("%s press 2\n",VAR_page_displaying.option_2);
>}
>
>PAGE input_page(void)
>
>{
>       PAGE page;
>
>       printf("\n");
>       printf("Page no please:");
>       scanf("%d",&page.no);
>
>       printf("\n");
>       printf("Enter text for story\n");
>       input(page.story, STORY_LENGTH);
>
>       printf("\n");
>       printf("Enter text for 1st Option:");
>       input(page.option_1, OPTION_1_LENGTH);
>       printf(" Enter page link for 1st Option:");
>       scanf("%d", &page.link_1);
>
>       printf("\n");
>       printf("Enter text for 2nd Option:");
>       input(page.option_2,OPTION_2_LENGTH);
>       printf(" Enter page link for 2nd Option");
>       scanf("%d", &page.link_2);
>
>       return(page);
>}
>/*must add a function to detect if page has been filled */
>void FUNCT_new_page(void)
>{
>        PAGE VAR_input_page;
>        int done=0;
>        char choice;
>        int pages_done[MAN_ARRAY_SIZE];
>        int i=0;
>
>        for(i=0;i<MAN_ARRAY_SIZE;i++) {
>                                      pages_done[i]=0;
>                                      }
>
>        i=0;
>
>        open_file(pages_done,MAN_ARRAY_SIZE);
>;
>/* a do while loop goes in here to allow many pages, page is created ,
>shown, ask if want to be saved and then ask if want new page or quit*/
>        do {
>
>
>           VAR_input_page=input_page();
>
>           pages_done[i++]=VAR_input_page.no;
>
>
>           printf("\n\n This is the page you just created:\n");
>           display_page(VAR_input_page);
>
>           printf("\n\n");
>
>           printf("Do you want to save it?(y/n)\n");
>           choice=getch();
>           if(choice=='y') {
>                           write_file((char *)&VAR_input_page,
>sizeof(VAR_input_page),VAR_input_page.no);
>                           }
>
>           printf("Do you want to continue adding pages(y/n)");
>           choice=getch();
>           if(choice=='n') {
>                           done=1;
>                           }
>           }while(!done);
>
>        close_file(pages_done,MAN_ARRAY_SIZE);
>}
>
>
>THIS SOURCE DEALS WITH THE DISK WRITE FUNCTIONS
>
>#include <stdio.h>
>#include <stdlib.h>
>
>static FILE *fptr;
>static int recsize;
>
>void open_file(int * pages_done, int array_size);
>void close_file(int * pages_done, int array_size);
>void write_file(char * strpointer, int page_size, int page_no);
>
>void open_file(int * pages_done, int array_size)
>{
>        int i=0;
>
>        if((fptr=fopen("chapter.dat", "r")) !=NULL) {
>
>fseek(fptr,0L,SEEK_SET);
>
>for(i=0;i<array_size;i++) {
>
>fscanf(fptr,"%d",*(pages_done++));
>
>}
>                                                      }
>        else if((fptr=fopen("chapter.dat","w+b")) !=NULL) {
>
>fseek(fptr,0L,SEEK_SET);
>
>for(i=0;i<array_size;i++) {
>
>fprintf(fptr,"%d",*(pages_done++));
>
>}
>                                                          }
>        else {
>             printf("Cannot open or start new chapter!!!");
>             exit(1);
>             }
>}
>
>
>
>
>void close_file(int * pages_done, int array_size)
>{
>        int i=0;
>
>        fseek(fptr,0L,SEEK_SET);
>        for(i=0;i<array_size;i++) {
>                                  fprintf(fptr,"%d",pages_done[i]);
>                                  }
>        fclose(fptr);
>}
>
>void write_file(char * strpointer, int page_size, int page_no)
>{
>        fseek(fptr,(page_no)*page_size ,SEEK_SET);
>        fwrite(strpointer, page_size, 1, fptr);
>}
>
>
>
>
>
>
>--
>comp.lang.c.moderated - clcm AT plethora DOT net


-- 
comp.lang.c.moderated - clcm AT plethora DOT net

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