Help plz - fopen()

Hello,

I have a problem here, I want to write a function called"myfopen()" instead of "fopen()"
for writing this function I must not use the <stdio.h> library,

Can you help me?

thanks a lot




I really needs your helps guys

No. fopen() returns a pointer to FILE. FILE is declared in <stdio.h>. You cannot return a pointer to FILE without using <stdio.h>.

What do you want the prototype for your myfopen() function to be?

myfopen(const char*, const char*)

I know that i should start to do it with open() and write() or read() but i am not really good at this, and i dont know how to start.

Compare the semantics and behaviour of fopen() with open() - your version will need to implement that missing functionality. You will need corresponding read, write and close operations as well - otherwise opening the file itself would be pointless. If you intend to use stdio fread/fwrite etc, then you will need implementation specific details of your particular libraries implementation.

It is not really reasonable to ask for help with so little initial effort. Since there are many design decisions that need to be made by you, and the scope of the task is significant. From the information you have provided, we would not really know where to start either.

There are a number of C libraries available as sourcecode that you might look at for inspiration. Here's one example I trust that on its own it will not help you too much (not least because it is written in K&R C rather than ISO/ANSI C, which is why I am happy to post the link as assistance rather than a solution. Your implementation will depend upon the scope and context of your particular assignment.

A prototype includes a return type

something like

thanks man

yes exactly,

it is a little comlicated because we will have the error cases, but for me it is just the beginning the problem,

this function will return the address 0 in case of the error,

and his jub is to open a stream andinitialize it

You have entirely missed bdb's point. FILE is a data structure defined by stdio.h. If it is your intent not to use stdio.h, you will have to define your own structure. Probably best in thsi case not to call it FILE but rather MYFILE perhaps.

The structure will contain anything your implementation needs to function in the manner you require, but I suggest that it will at least contain the file descriptor or handle returned by open().

No man i got it,
i already defined that :

typedef struct
{
int index;
int number_char_buff;
char buffer[BUFSIZE];


} myFILE;

an d i knew that i must use th e open() function instead of fopen()
but for the beginning i had problems i did sth but i am not sure that it is a good way or not, the problem is the time

this is it nt complete yet,

myFILE* myfopen(const char* name_file, const char* options)
{
char* adress_r=strchr(options,'r');
char* adress_w=strchr(options,'w');
char* adress_a=strchr(options,'a');
char* adress_t=strchr(options,'t');
myFILE *stream=NULL;
if ( adress_r== NULL && adress_w == NULL ) /* If r and w are not in options */
{
/*ERROOOOOOOOOOOOR !;*/

}
else if ( adress_r!= NULL && adress_w != NULL ) /* If r and w are in options*/
{} /*ERROOOOOOOOOOOOR !;*/
else if (adress_r != NULL) /* If just r is in options*/
{

stream=(myFILE*)malloc(sizeof(myFILE));
stream->index=open(name_file,O_RDONLY);


if (stream->index <0)
{
fatal(0,"This file do not exist \n \0", 5);
}
}
else if ( adress_a != NULL && adress_t != NULL ) /* If a and t are in otions*/
{} /*ERROOOOOOOOOOOOR !;*/
else if ( adress_a == NULL && adress_t == NULL ) /* If just w is in otions*/
{
stream=(myFILE*)malloc(sizeof(myFILE));
stream->index=open(name_file,O_CREAT|O_WRONLY,S_IRUSR|S_IWUSR|S_IROTH);
}
else if( adress_a != NULL) /* If just w and a are in otions*/
{
stream=(myFILE*)malloc(sizeof(myFILE));
stream->index=open(name_file,O_CREAT|O_WRONLY|O_APPEND,S_IRUSR|S_IWUSR|S_IROTH);
}
else /* If just w and t are in otions*/
{
stream=(myFILE*)malloc(sizeof(myFILE));
stream->index=open(name_file,O_CREAT|O_WRONLY|O_TRUNC,S_IRUSR|S_IWUSR|S_IROTH);
}

return stream;

}