Pointer Questions

1, a pointer (here "pointer") points to a data stream to a file is located.
2, A variable (in this case "m)", then how many numbers there are.
3 m to retire pointer back to the beginning point also.
4 data output.
But the code does not work as-planned. The is the first value only.
Who can help me?
Thanks

Code:

# include <stdio.h> 
# Include <stdlib.h> 
int main () 
( 
char * pointer, 
unsigned char m = 0; 
FILE * file, 
file = fopen ("data.txt", "rt") 
while ((fscanf (file, "% d", pointer))! = EOF) 
( 
pointer + +; 
m + +; 
) 
fclose (file); 

pointer = pointer - m, / / Pointer to withdraw 

while ((* pointer)! = NULL) 
( 
printf ("% d \ t", * pointer) / / output data 
pointer + +; 
) 
)

 

pointer has no memory!

should you allocate memory with malloc, since otherwise the pointer showing nirvana! nirvana and the data write is not good

 

Did you "pointer = (char *) malloc (sizeof (char ));"?
I have used, but that does not help.
Can you give me the full code?
Thanks

 

malloc (sizeof (char)) provides you space for a char ... you need but probably more ... So it must malloc (n * sizeof (char)) where n is the number is called.

 

char instead of int Why? You read% d end of ints.
Have you ever thought of using a tuned array?
Why do you break from the output at 0? Why do you write NULL instead of 0?

sizeof (char) is always a way, and should never be explicitly written out.

The return value of malloc should not cast according to some experts, are also, in any case, it's at least useless.

 

Hi,
I have rewritten the program. Seems to be better. The only problem is I get a unendlose loop. So the "\ 0" is
definitely not true, but what is the right one? What is the difference btwn NULL, EOF and "\ 0"?

Code:

# include <stdio.h> 
# Include <stdlib.h> 
int main () 
( 
int * pointer, 
unsigned char m = 0; 
FILE * file, 
int character 
file = fopen ("data.txt", "rt") 
while ((fscanf (file, "% d", & sign) ) = EOF) 
( 
(pointer + m) = sign *, 
m + +; 
) 
fclose (file); 

m = 0; 
while ((pointer + m)! = '\ 0') 
( 
printf ("% d \ t" , * (pointer + m)) 
m + +; 
) 
)

 

hand still has no memory: (

Hoer times n bit Bashar.

NULL is the same as (void *) 0 - and is usually used to say that this pointer is invalid '. "

EOF - End Of File, indicates that the file is zueende.

"\ 0" is a string (char *) with the following contents, '\ 0' "\ 0 'well what do you think is more
"\ 0 'which has the value 0 and indicates the end of the strings!