File *f[i] array?

[chico1st]

how do i make a FILE pointer array in C?

i tried this but it didnt work, i ment to post this a while ago but i think i got distracted.

[kryptkat]

you can only have one file open at a time.

[cpjust]

kryptkat> you can only have one file open at a time.

Where did you hear that?

chico1st> i tried this but it didnt work

If you show the code you tried, we could help you determine the problem.

[MacGyver]

Yeah, that one file opened at a time thing is totally wrong. You can open as many files as the underlying system permits you to, which is usually way more than just one.

As for how to make the array, make it like you would any other array.

[KIBO]

You can have FOPEN_MAX files open, check your compiler to see how big that is.

for instance, fopen on my system is implemented like this:

FILE *fopen (const char *filename, const char *opentype)
{
    register int filenumber;

    for (filenumber=START_FILE; filenumber<FOPEN_MAX; filenumber++)
        if ((&_iob[filenumber])->_flag == 0)	/* look for free ele. in _iob */
	    return _fopen (filename, opentype, &_iob[filenumber]);
    return (NULL) ;			/* No free elements in _iob structure */
}

It just looks through its internal

FILE _iob[FOPEN_MAX] array to find the first unopened file. If all are opened NULL is returned

[ozumsafa]

Yeah , for example mine can open 256 .

isnt it too much =) ?

[chico1st]

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

void main(){
	FILE *xyz;
	int i;
	int INCREMENT = 5;

	xyz = malloc(sizeof(FILE) * INCREMENT);
	for (i = 0; i < INCREMENT; i++) {
		xyz[i] = malloc(sizeof(FILE));
	}

}

here are the errors

C:\Files.c(11) : error C2115: '=' : incompatible types
Error executing cl.exe.

[Salem]

main returns an int - always.

You can't malloc a number of FILE's because FILE is an incomplete type. That is, you're only ever allowed to POINT to a FILE.

Further, the only functions which can initialise a FILE* pointer for you are
fopen
freopen
popen

Perhaps start with
FILE *myFiles[5];
myFiles[0] = fopen("foo.txt", "r" );

Then graduate to
FILE **myFiles = malloc ( 5 * sizeof *myFiles );

[chico1st]

ok i tried this:

int main(){
	FILE *f[20];
	FILE *fbin;
	char *FileName[1024];
	char *Holder[1024];
	int i;
	int NumberOfFiles = 20;

	for (i=0; i<NumberOfFiles; i++){
		strcpy(FileName,"Channel");
		itoa(i, Holder, 10);
		strcat(FileName, Holder);
		strcat(FileName, ".txt");
		f[i] = fopen(FileName,"r+");
	}


}

but i get these warnings... what is going on?

C:\Files.c(14) : warning C4047: 'function' : 'char *' differs in levels of indirection from 'char *[1024]'
C:\Files.c(14) : warning C4024: 'strcpy' : different types for formal and actual parameter 1

[Salem]

Your inability to read error messages, and generally declare arrays for storing chars.

Drop the * from your two char arrays.

Simply spraying "*" all over the place because you think there is a pointer involved somewhere isn't the way to go.

[maxorator]

ok i tried this:

int main(){
	FILE *f[20];
	FILE *fbin;
	char *FileName[1024];
	char *Holder[1024];
	int i;
	int NumberOfFiles = 20;

	for (i=0; i<NumberOfFiles; i++){
		strcpy(FileName,"Channel");
		itoa(i, Holder, 10);
		strcat(FileName, Holder);
		strcat(FileName, ".txt");
		f[i] = fopen(FileName,"r+");
	}


}

but i get these warnings... what is going on?

Yikes.
Remember that char* wah[1024] basically equals to char** wah which is not what you want. Array variable itself is a pointer, that extra * does not fit there. Just use char wah[1024]. And I noticed that in your previous code you used malloc but didn't free the buffer you allocated which is very bad.

[matsp]

I would use "sprintf()" to form the filename, rather than the list of strcpy/strcat -- see the example I posted previously on how to merge your files.

--
Mats

[zacs7]

Also sizeof(Holder) + 4 > sizeof(FileName), potential segfault ,

Use sprintf as matsp said, and limit the size of Holder, so it and it's extension can fit into FileName.

[kryptkat]

Was thinking that the op wanted to do something like

FILE *filepointer[numb]

an array of file pointers....and was thinking file could only be used by one prog at a time....

[bean66]

try:

int main(){
	FILE *f[20];
	char FileName[20];  /* Plenty large for your file naming */
	int i;
	int NumberOfFiles = 20;

	for (i=0; i<NumberOfFiles; i++){
                         sprintf(FileName,"Channel%d.txt",i);
                         f[i] = fopen(FileName,"r+");
	}


}