problem in reading file using fread - High Level Programming

arunkumar_mca · #1 10-27-2006

Hi All,

These are the two ways i tried to read file but i getting work with second one not with the first.

char buf[2000]; // Defining space for buf
ctrlfnum = fopen(filename_arr.control_fname,"r");

1) n = fread(buf,sizeof(buf),1,ctrlfnum); ============== (not works)
2) n = fread(buf,1000,1,ctrlfnum); ================== (Works)

NOTE : i'm using HP-UX C++.

Awaiting reply. Thanks in advance.

Thanks

jim mcnamara · #2 10-28-2006

sizeof(a pointer to something) = size of a pointer variable, = 4 on a 32 bit machine.
sizeof(buf) is likely 4, not 1000.

arunkumar_mca · #3 10-30-2006

Thanks man,, I got what are yoy saying ...Thanks a lot ..

Can you please suggest can i make it works by fread .

Thanks in advance ,
Arun Kumar

jim mcnamara · #4 10-30-2006

You need to have a way to know the maximum size of buf.
Try something global like a define.

Code:

#define REC_SZ 1000
......
int foo()
{
    char buf[REC_SZ]={0x0};
    bar(buf);
}

char *bar(char *buf)
{
.............
     fread(buf,REC_SZ,1,ctrlfnum); 

     return *buf;
}

odys · #5 10-30-2006

Quote:

Originally Posted by jim mcnamara

sizeof(a pointer to something) = size of a pointer variable, = 4 on a 32 bit machine.
sizeof(buf) is likely 4, not 1000.

char *buf;
sizeof(buf) => 4

char buf[2000];
sizeof(buf) => 2000

Regards

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