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reading strings from file

P: n/a
Hi

I have this problem that I can't solve, I know it shouldn't be hard but
I'm not a good coder and I'm going crazy tonight...

I have a txt file that goes like this:

string1 string2
string3 string4

I'd like to read it and store string1 and string in array1 and string2
and 4 in array2

can u please advice me the right way to do this? I'm using C/unix

thanks a lot and I wish u all a great 2006
--
there are no numbers in my email address
Jan 2 '06 #1
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6 Replies


P: n/a
Giff a écrit :
I have this problem that I can't solve, I know it shouldn't be hard
but I'm not a good coder and I'm going crazy tonight...

I have a txt file that goes like this:

string1 string2 string3 string4
Do you meant:

string1<blank>string2<EOL>
string3<blank>string4<EOL>

?
I'd like to read it and store string1 and string in array1 and
string2 and 4 in array2


You can use each line with fgets() and then extract the strings with
sscanf() and "%s %s". Make sure that sscanf() returns 2.

You can store the result in an array of strings with a fixed width (2D
array of char) or allocate the required space (malloc()) to store the
strings, and to store the addresses of the allocated blocks on an array
of pointers to char. This array could also be dynamically allocated. All
depends on the required flexibility.
--
A+

Emmanuel Delahaye
Jan 2 '06 #2

P: n/a
Emmanuel Delahaye ha scritto:

Do you meant: string1<blank>string2<EOL>
string3<blank>string4<EOL> ?
exactly, thanks for replying

You can use each line with fgets() and then extract the strings with
sscanf() and "%s %s". Make sure that sscanf() returns 2.


I was trying with fscanf, now I tried the way u suggested with no results:

char *array1[2], *array2[2],buff[512];
FILE *f;

i=0;
do {

if ( fgets(buff,sizeof(buff),f)==NULL ) perror("fgets");
if ( (i = sscanf(buff,"%s %s",array1[i],array2[i])) printf("%d\n",i);
i++;
}while(i<2);

it opens the file correctly but then the sscanf returns 0, it gets stuck
during the second iteraction of the do-while

I'm sure I'm doing some really stupid mistakes, I'm not experienced,I've
been coding the whole day and this should be working tomorrow

thanks a lot

--

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http://www.newsland.it/news segnala gli abusi ad ab***@newsland.it
Jan 2 '06 #3

P: n/a
At about the time of 1/2/2006 2:14 PM, Giff stated the following:
Hi

I have this problem that I can't solve, I know it shouldn't be hard but
I'm not a good coder and I'm going crazy tonight...

I have a txt file that goes like this:

string1 string2
string3 string4

I'd like to read it and store string1 and string in array1 and string2
and 4 in array2

can u please advice me the right way to do this? I'm using C/unix

thanks a lot and I wish u all a great 2006


The only what that I can think of is to read in the lines one at a time
using fgets and then using strsep to split the strings apart. Just out
of curiosity, did you write this text file or was it provided from an
outside source?

--
Daniel Rudy

Email address has been base64 encoded to reduce spam
Decode email address using b64decode or uudecode -m

Why geeks like computers: look chat date touch grep make unzip
strip view finger mount fcsk more fcsk yes spray umount sleep
Jan 2 '06 #4

P: n/a
Giff <gi*********@gmail456.com> schrieb:
char *array1[2], *array2[2],buff[512];
FILE *f;

i=0;
do {

if ( fgets(buff,sizeof(buff),f)==NULL ) perror("fgets");
if ( (i = sscanf(buff,"%s %s",array1[i],array2[i])) printf("%d\n",i);
Where did you allocate memory for array1 and array2?
i++;
}while(i<2);

I'm sure I'm doing some really stupid mistakes, I'm not experienced,I've
been coding the whole day and this should be working tomorrow


If you are using pointers, you should have a look at malloc or calloc.

Markus
Jan 2 '06 #5

P: n/a
The only what that I can think of is to read in the lines one at a time
using fgets and then using strsep to split the strings apart. Just out
of curiosity, did you write this text file or was it provided from an
outside source?


hi all, I made it work now! I'm not very good with array and pointers, I
mixed them up a bit

thanks a lot to everybody and again happy new year!

--

questo articolo e` stato inviato via web dal servizio gratuito
http://www.newsland.it/news segnala gli abusi ad ab***@newsland.it
Jan 2 '06 #6

P: n/a
At about the time of 1/2/2006 3:17 PM, Giff stated the following:
Emmanuel Delahaye ha scritto:
Do you meant:


string1<blank>string2<EOL>
string3<blank>string4<EOL>


?

exactly, thanks for replying
You can use each line with fgets() and then extract the strings with
sscanf() and "%s %s". Make sure that sscanf() returns 2.

I was trying with fscanf, now I tried the way u suggested with no results:

char *array1[2], *array2[2],buff[512];
FILE *f;

i=0;
do {

if ( fgets(buff,sizeof(buff),f)==NULL ) perror("fgets");
if ( (i = sscanf(buff,"%s %s",array1[i],array2[i])) printf("%d\n",i);
i++;
}while(i<2);

it opens the file correctly but then the sscanf returns 0, it gets stuck
during the second iteraction of the do-while

I'm sure I'm doing some really stupid mistakes, I'm not experienced,I've
been coding the whole day and this should be working tomorrow

thanks a lot


I would do something like this...

#define MAX_ARRAY 2 /* number of strings to store */
#define MAX_CHAR 64 /* storage size of each string */
#define MAX_BUFF 512 /* input buffer size */

char array1[MAX_ARRAY][MAX_CHAR];
char array2[MAX_ARRAY][MAX_CHAR];
char buff[MAX_BUFF];
FILE *f;

for (i = 0; i < MAX_ARRAY; ++i)
{
ptr = fgets(buff, sizeof(buff), f);
if (ptr == NULL) perror("fgets");
j = sscanf(buff, "%s %s", &array1[i], &array2[i]);
if (j != 2) perror("sscanf");
}
This is a guideline and it may or may not work correctly. The problem
that I see with your code is that you are defining the arrays as a
pointer. No storage has been allocated to hold the actual data. Your
usage of sscanf with the pointers is correct as far as I can tell, but
those pointers need to point to something. As it is, sscanf writes the
strings to random locations in memory. I'm amazed that you didn't get a
general protection fault or a segmentation fault when you ran this.

Also, arrays of strings are a little strange because a single string is
in itself an array of char, so to allocate an array of strings, you need
a 2 dimensional array of char.
--
Daniel Rudy

Email address has been base64 encoded to reduce spam
Decode email address using b64decode or uudecode -m

Why geeks like computers: look chat date touch grep make unzip
strip view finger mount fcsk more fcsk yes spray umount sleep
Jan 3 '06 #7

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