Help needed again

[Dark-Byte]

Hello I'm writing a program in C to read from a file and write to standard output but it is giving me something like this:
���p�
���DB�ο8�
���� ��ο�P� ����p��P�οD�ο��
�
�� ���οb�
��
�
�(��p������
p ���p����������P[�p[�������������
����

Here is the code:



int main()
{
char holding[1000];
int x;
x = open( "/home/user/Desktop/Labsheets/Labsheet4/input.dat", O_RDONLY, S_IRWXU );
int i;
i = lseek( x, 0, SEEK_END );//get number of bytes in file
read( x, holding, i );
close( x );
printf
return 0;
}


Can someone help me please?

[johnl]

Is your file a plain text file? If not, it makes no sense to print the contents of the file.

Otherwise, I would check the return values of open() and read() to make sure it is actually opening the file and actually reading some bytes. Also make sure that you are null-terminating the buffer (I don't think read() does this for you).

[MadCow108]

your setting the position in the file to the end with your lseek
so you need to reset it before reading:
lseek(x,0,SEEK_SET);


int main()
{
char holding[1000];
int x;
x = open( "test.c", O_RDONLY);
int i;
i = lseek( x, 0, SEEK_END );
lseek(x,0,SEEK_SET); // seek to start
int r = read( x, holding, i );
holding[r] = '\0'; // null terminate
close( x );
printf("%s",holding);
return 0;
}

this is of course not very effective.
it would be simpler to just read into your buffer until you encounter EOF (or end of buffer or error) with the fread/fget/... functions

[Dark-Byte]

your setting the position in the file to the end with your lseek
so you need to reset it before reading:
lseek(x,0,SEEK_SET);


int main()
{
char holding[1000];
int x;
x = open( "test.c", O_RDONLY);
int i;
i = lseek( x, 0, SEEK_END );
lseek(x,0,SEEK_SET); // seek to start
int r = read( x, holding, i );
holding[r] = '\0'; // null terminate
close( x );
printf("%s",holding);
return 0;
}


Very true!!Thanks a lot to both of you.

[Can+~]

Why are you using the unistd file functions instead of the C standard functions?

[Dark-Byte]

Beacuse I got tons of labsheet from my university which says to use only those functions(system calls ):


open
close
read
write
lseek

:(