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Standard I/O streams....fopen fprintf fscanf fclose

  • frankly
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Post March 19th, 2003, 12:54 am

Hi ppl,

I got a little problem of reading data from the file...just a little problem I guess but I really don't know where to start fixing it
I use this to write into a file
Code: [ Select ]
void Send_field1(filename, field)
char *filename;
FIELD2N *field;
{
INDEX i;
FILE *fptr;
if ((fptr = fopen(filename, "a")) == NULL)
printf("Error opening file\n");
printf("before printing\n");
SUMLOOP(i) fprintf(fptr, "%8x ", field->e[i]);
if (fclose(fptr) == EOF)
printf("Error closing file\n");
}
  1. void Send_field1(filename, field)
  2. char *filename;
  3. FIELD2N *field;
  4. {
  5. INDEX i;
  6. FILE *fptr;
  7. if ((fptr = fopen(filename, "a")) == NULL)
  8. printf("Error opening file\n");
  9. printf("before printing\n");
  10. SUMLOOP(i) fprintf(fptr, "%8x ", field->e[i]);
  11. if (fclose(fptr) == EOF)
  12. printf("Error closing file\n");
  13. }

where SUMLOOP is a loop from i=0 to the number of entries in the array, don't worry about that one, it's clean. :wink:

and I wrote sth into the file, yes prefectly fine and I opened it and see this
Code: [ Select ]
  547d baf7930d 3c21e169 a860ceee   547d baf7930d 3c21e169 a860ceee

yes hexademcial...
and I wrote this to read it back
Code: [ Select ]
void Receive_field1(filename, field)
char *filename;
FIELD2N *field;
{
INDEX i;
FILE *fptr;
if ((fptr = fopen(filename, "r")) == NULL)
printf("Error opening file\n");
printf("before reading\n");
SUMLOOP(i) {fscanf(fptr, "%8x ", &field->e[i]); printf("field->e[i] %8x\n", &field->e[i]);}
if (fclose(fptr) == EOF)
printf("Error closing file\n");
}
  1. void Receive_field1(filename, field)
  2. char *filename;
  3. FIELD2N *field;
  4. {
  5. INDEX i;
  6. FILE *fptr;
  7. if ((fptr = fopen(filename, "r")) == NULL)
  8. printf("Error opening file\n");
  9. printf("before reading\n");
  10. SUMLOOP(i) {fscanf(fptr, "%8x ", &field->e[i]); printf("field->e[i] %8x\n", &field->e[i]);}
  11. if (fclose(fptr) == EOF)
  12. printf("Error closing file\n");
  13. }


u can see I tried to print out the thing that I got....and all I got is this......
Code: [ Select ]
field->e[i] 241ff00
field->e[i] 241ff04
field->e[i] 241ff08
field->e[i] 241ff0c
  1. field->e[i] 241ff00
  2. field->e[i] 241ff04
  3. field->e[i] 241ff08
  4. field->e[i] 241ff0c


Anyone knows what's gonig on here? 8O
Thanz!! :D
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Post March 19th, 2003, 12:54 am

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Post March 19th, 2003, 3:31 am

I am not sure what is going on yet, but I do notice that

Code: [ Select ]
field->e[i] 241ff00
field->e[i] 241ff04
field->e[i] 241ff08
field->e[i] 241ff0c
  1. field->e[i] 241ff00
  2. field->e[i] 241ff04
  3. field->e[i] 241ff08
  4. field->e[i] 241ff0c

is increasing each time by exactly 0x4
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  • frankly
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Post March 19th, 2003, 4:10 am

O hey !! good point!!
so.....is this....simply an address or what?
my codes r hard to understand huh? haha
but i really don't know where is the problem.....it's just a smiple fscanf... :shock:
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Post March 19th, 2003, 4:13 am

OK now i get this
Code: [ Select ]
field->e[i] 77c39348
field->e[i]  223b20
field->e[i]  223b08
field->e[i]    8
  1. field->e[i] 77c39348
  2. field->e[i]  223b20
  3. field->e[i]  223b08
  4. field->e[i]    8

after changing the &field to field coz &field is simply the address...but still the data read from the file is not the same as that write into it
what is wrong here? :shock:
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Post March 19th, 2003, 6:21 am

o...I think I didnlt make it very clear hehe
actually I want a array with four entries to input the data read from the feil
so the array with have the first entry as
Code: [ Select ]
547d

the second being
Code: [ Select ]
baf7930d
the third being
Code: [ Select ]
3c21e169
and the last being
Code: [ Select ]
a860ceee


The number of entries vary so I can't really define it....
so........any idea?
Thanz!! :D
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Post March 20th, 2003, 6:25 am

O....I think it might be due to the pointer problems....
ok here's the new version of the functions, actually they're about the same
the writing function is like this
Code: [ Select ]
void Send_field1(filename, field)
char *filename;
FIELD2N *field;
{
INDEX i;
FILE *fptr;
if ((fptr = fopen(filename, "a")) == NULL)
printf("Error opening file\n");
printf("before printing\n");
SUMLOOP(i) fprintf(fptr, "%04x ", field->e[i]);
if (fclose(fptr) == EOF)
printf("Error closing file\n");
}
  1. void Send_field1(filename, field)
  2. char *filename;
  3. FIELD2N *field;
  4. {
  5. INDEX i;
  6. FILE *fptr;
  7. if ((fptr = fopen(filename, "a")) == NULL)
  8. printf("Error opening file\n");
  9. printf("before printing\n");
  10. SUMLOOP(i) fprintf(fptr, "%04x ", field->e[i]);
  11. if (fclose(fptr) == EOF)
  12. printf("Error closing file\n");
  13. }

and the reading part is like this
Code: [ Select ]
void Receive_field1(filename, field)
char *filename;
FIELD2N *field;
{
INDEX i;
FILE *fptr;
if ((fptr = fopen(filename, "r")) == NULL)
printf("Error opening file\n");
printf("before reading\n");
SUMLOOP(i) {fscanf(fptr, "%x ", &field->e[i]); printf("field->e[i] %04x\n", field->e[i]);}
if (fclose(fptr) == EOF)
printf("Error closing file\n");
}
  1. void Receive_field1(filename, field)
  2. char *filename;
  3. FIELD2N *field;
  4. {
  5. INDEX i;
  6. FILE *fptr;
  7. if ((fptr = fopen(filename, "r")) == NULL)
  8. printf("Error opening file\n");
  9. printf("before reading\n");
  10. SUMLOOP(i) {fscanf(fptr, "%x ", &field->e[i]); printf("field->e[i] %04x\n", field->e[i]);}
  11. if (fclose(fptr) == EOF)
  12. printf("Error closing file\n");
  13. }

I wrote sth into the file and the wriing part is perfectly ok as before
I wrote
Code: [ Select ]
685 43c6fffc e02152ec 87fd5959

yes a bit messy, it's a random hexadecimal

But when I tried to see what the readinf function read from the file...I got this
Code: [ Select ]
77c39348  223b20  223b08    8

so it is still not reading the right thing

And here's some of the declarations I made beforehand
Code: [ Select ]
typedef struct {
  ELEMENT  e[MAXLONG];
} FIELD2N;
  1. typedef struct {
  2.   ELEMENT  e[MAXLONG];
  3. } FIELD2N;

where MAXLONG = 4
and that SUMLOOP is defined as
Code: [ Select ]
#define SUMLOOP(i)  for(i=0; i<MAXLONG; i++)

simply a way to define the loop which will be frequenylt used in the program :D

So anyone got any idea about where it went wrong? :shock:
Thanz!! :D
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Post March 20th, 2003, 10:06 am

O.......ok hehe.........I think I finally solved that....and I'm teribly sorry...coz that was just a typo of the "filename" that I set. So yes u guyz shouldn't have noticed that coz I didn't post that part here.....took me long to realise that too

Thanz anywayz!! :D

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