file i/o problem

king_of_inismac · 02-07-2004 11:28AM #1

file I/O problem, The data is written to file correctly, but not read back correctly:

int store_data(char* path)
{
FILE *out;
out = fopen(path, "w");
if(out == null)
{
//display error messagebox
}

fprintf(out, "%d", time); //time is a global variable

fclose(out);
}

int read_data(char* path)
{
FILE *in;
in = fopen(path, "r");
if(in == null)
{
//display error messagebox
}

fscanf(in, "%d", &new_variable); //new variable is a global variable

fclose(in);

}

Ive simplified the code a good bit, but this is basically what I'm doing.

The new_variable is not being set, even tho the file is written to correctly..

anyone spot a mistake?

Thanks,
king

Repli · 02-07-2004 11:38AM

Post up where you call the functions from main()
tbh i find i/o a lot easier in C++ - can post up some code to do same thing if u like

Just noticed something - you arent returning ints in your functions

king_of_inismac · 02-07-2004 11:50AM

The application is win32.

The functions are called from MainWndProc

code goes like this:

switch(msg) {

switch(LOWORD(wParam))
{
case IDC_FILE_SAVE:

r = save_as(hwnd);
break;
case IDC_FILE_OPEN:
r = open_file(hwnd);
break; .....
}

got the following two functions off the net. They basically pop up the proper dialogs and get the filenames, which are passed to the functions described in my first post:

int save_as(HWND main_window)
{
char t_text[2056];
OPENFILENAME t_save_file;

memset(&t_text, 0, sizeof(t_text));
memset(&t_save_file, 0, sizeof(OPENFILENAME));
t_save_file.lStructSize = sizeof(OPENFILENAME);
t_save_file.hwndOwner = main_window;
t_save_file.lpstrFilter = FILTER;
t_save_file.lpstrFile = g_long_filename;
t_save_file.nMaxFile = sizeof(g_long_filename);
t_save_file.lpstrFileTitle = g_short_filename;
t_save_file.nMaxFileTitle = sizeof(g_short_filename);
t_save_file.Flags = OFN_CREATEPROMPT | OFN_NOREADONLYRETURN | OFN_OVERWRITEPROMPT | OFN_PATHMUSTEXIST;
t_save_file.lpstrDefExt = DEF_EXTENSION;
if(0 == GetSaveFileName(&t_save_file)) {
if(0 != CommDlgExtendedError())
return -1;
else
return 1;
}

memset(t_text, 0, sizeof(t_text));

//heres where I call my function

store_data(g_long_filename);

return 0;
}

int open_file(HWND main_window)
{
char t_text[2000];
OPENFILENAME t_open_file;

memset(&t_text, 0, sizeof(t_text));
memset(&t_open_file, 0, sizeof(OPENFILENAME));
t_open_file.lStructSize = sizeof(OPENFILENAME);
t_open_file.hwndOwner = main_window;
t_open_file.lpstrFilter = FILTER;
t_open_file.lpstrFile = g_long_filename;
t_open_file.nMaxFile = sizeof(g_long_filename);
t_open_file.lpstrFileTitle = g_short_filename;
t_open_file.nMaxFileTitle = sizeof(g_short_filename);
t_open_file.Flags = OFN_CREATEPROMPT | OFN_NOREADONLYRETURN | OFN_PATHMUSTEXIST;
t_open_file.lpstrDefExt = DEF_EXTENSION;
if(0 == GetOpenFileName(&t_open_file)) {
if(0 != CommDlgExtendedError())
return -1;
else
return 1;
}

memset(t_text, 0, sizeof(t_text));

//heres where I call my function
read_file(g_long_filename);

return 0;
}

ideas?

ps: about the ints, I know, am a lazy git, just want to get the thing running, don't think it makes a difference?

Repli · 02-07-2004 11:54AM

Ah - I dont use WinAPI - much prefer MFC
anyway try changing the return types of your functions to voids, or else use this code:

[php]
void store_data ( char *path )
{
ofstream out( path );

if ( out.fail() )
// error message

out << time;

out.close();
}

void read_data ( char *path )
{
ifstream in( path );

if ( in.fail() )
// error message

in >> new_variable;

in.close();
}
[/php]

king_of_inismac · 02-07-2004 12:02PM

Thanks man,

Ya prefer MFCs myself, but I'm working with soem *redundant* software.

BTW,What library do I need to include to use those functions?

Repli · 02-07-2004 12:21PM

You will need:
#include <fstream>

and probably
#include <iostream>

king_of_inismac · 02-07-2004 12:31PM

Thanks Repli,

Would still like o know what the problem is with the C code,

Has anyone else any ideas?

Thanks, king

file i/o problem

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