read writte to file

[Carramba]

#include <stdio.h>

int main( void ){
char cQuit = 'a';
char cKommando , artistNamn[80] , skivansNamn[80] , cChar;
int cK ;
FILE *pekaFile;

printf( "l - for read file\n");
printf( "s - for writte file\n");
printf( "q - quite\n");

while( cQuit != 'q' ){

if( cKommando == 'l' || cKommando == 'L' ){

if( ( pekaFile = fopen( "registret.txt" ,"r" ) ) == NULL )
//works just fine
{
printf("Can't open file \n" );
exit(1);
}
printf( "\nCD register \n\n" );
printf( "ARTIST NAMN \n" );
do
{
cChar = fgetc( pekaFile );
putchar( cChar );
} while ( cChar != EOF);
fclose( pekaFile );
printf( "\n");
}
else if( cKommando == 's' || cKommando == 'S' ){

printf("Type artist name: ");
scanf("%s",arti stNamn); //<<<=problem here can't input more
that one word in string
printf("Type cd titel: ");
scanf("%s",skiv ansNamn);//<<<=problem here can't input more
that one word in string

if( ( pekaFile = fopen("registre t.txt","a" ) ) == NULL )
{
printf( "Can't open file \n" );
exit( 1 );
}

fprintf( pekaFile, "%s %s\n", artistNamn, skivansNamn );
//<<<= or here can't writte more that one word in string?!

fclose( pekaFile );
}
printf("Command me: "); //<<<== gets printed 2 times, why?
cQuit = cKommando;
cK = getchar();
cKommando = (char)cK;
}
}/* END main */
--

Thanx in advance
_______________ _________
BTW. I know my english is not best in the word, so please stop bugging me
about my spelling. And yes Iam sorry you don't understand what I mean, but
there is no point to yell at me. Have a nice day.

[Michael Mair]

Carramba wrote:

#include <stdio.h>

int main( void ){
char cQuit = 'a';
char cKommando , artistNamn[80] , skivansNamn[80] , cChar;
It is usually better not to use magic numbers, i.e.
#define NAMELEN 80
and
char artistNamn[NAMELEN + 1], ....
are usually better (the +1 is for the string terminator '\0'
and stems from the fact that there are often comparisons against
the string length; for this, one can use NAMELEN).
int cK ;
FILE *pekaFile;

printf( "l - for read file\n");
printf( "s - for writte file\n");
printf( "q - quite\n");

while( cQuit != 'q' ){

if( cKommando == 'l' || cKommando == 'L' ){
You use cKommando without having initialised it or assigned to it.

if( ( pekaFile = fopen( "registret.txt" ,"r" ) ) == NULL )
//works just fine
{
printf("Can't open file \n" );
exit(1);
You call exit without having included <stdlib.h>; moreover, you
use an at best implementation defined argument value.
The standard gives you 0, EXIT_SUCCESS and EXIT_FAILURE.
}
printf( "\nCD register \n\n" );
printf( "ARTIST NAMN \n" );
do
{
cChar = fgetc( pekaFile );
Your are assigning the int return value to a char variable.
This may well lead to your losing information or wading into
the realm of undefined behaviour.
Use int as type for single characters:
int cChar
putchar( cChar );
} while ( cChar != EOF);
This is the wrong way round.
EOF is usually not representable by char cChar (and should not
be output as it is no character but an indicator value).
Use
while ((cChar = fgetc(pekaFile) ) != EOF)
{
putchar(cChar);
}
This works always if cChar is of type int.

Note: The macro getc can replace the call to fgetc() in this
case; getc is often more efficient.
fclose( pekaFile );
printf( "\n");
}
else if( cKommando == 's' || cKommando == 'S' ){
once again, cKommando is not initialised the first time.

printf("Type artist name: ");
scanf("%s",arti stNamn); //<<<=problem here can't input
more that one word in string
printf("Type cd titel: ");
scanf("%s",skiv ansNamn);//<<<=problem here can't input
more that one word in string
Note: Using scanf() without checking the return value almost
always is a sign that you did not give enough thought.
You can read your line using fgets() or Pop's device(*) (whichever
is more to your liking) or make use of one function out of a
host of nonstandard replacements -- neither fgets() nor scanf()
are well designed.
In your above invocation, you also are inviting trouble for overly
long input (->buffer overflow).

if( ( pekaFile = fopen("registre t.txt","a" ) ) == NULL )
{
printf( "Can't open file \n" );
exit( 1 );
}

fprintf( pekaFile, "%s %s\n", artistNamn, skivansNamn );
//<<<= or here can't writte more that one word in string?!

fclose( pekaFile );
}
During program development, it often is a good idea to catch
or at least trace the impossible case, i.e.

else {
fprintf(stderr, "cKommando was neither l/L nor s/S!\n");
}

In this case, it may not necessarily have enlightened you...
printf("Command me: "); //<<<== gets printed 2 times, why?
cQuit = cKommando;
cK = getchar();
You are mixing scanf() und getchar() for input from stdin.
This is not a good idea, as scanf() leaves "trash" on the input.
Please read the comp.lang.c FAQ on scanf() and getchar() and
their proper use.
BTW: Usually, one reads or skims the FAQ _before_ posting.
cKommando = (char)cK;
}
No int return.
}/* END main */

(*) Pop's Device: search the comp.lang.c archives with groups.google.
Cheers
Michael
--
E-Mail: Mine is an /at/ gmx /dot/ de address.

[pete]

Carramba wrote:

#include <stdio.h>

int main( void ){
char cQuit = 'a';
char cKommando , artistNamn[80] , skivansNamn[80] , cChar;
int cK ;
FILE *pekaFile;

printf( "l - for read file\n");
printf( "s - for writte file\n");
printf( "q - quite\n");

while( cQuit != 'q' ){

if( cKommando == 'l' || cKommando == 'L' ){

if( ( pekaFile = fopen( "registret.txt" ,"r" ) ) == NULL )
//works just fine
{
printf("Can't open file \n" );
exit(1);
}

printf( "\nCD register \n\n" );
printf( "ARTIST NAMN \n" );
do
{
cChar = fgetc( pekaFile );
putchar( cChar );
} while ( cChar != EOF);
fclose( pekaFile );
printf( "\n");
}

else if( cKommando == 's' || cKommando == 'S' ){

printf("Type artist name: ");
scanf("%s",arti stNamn); //<<<=problem here can't input more
that one word in string
printf("Type cd titel: ");
scanf("%s",skiv ansNamn);//<<<=problem here can't input more
that one word in string

if( ( pekaFile = fopen("registre t.txt","a" ) ) == NULL )
{
printf( "Can't open file \n" );
exit( 1 );
}

fprintf( pekaFile, "%s %s\n", artistNamn, skivansNamn );
//<<<= or here can't writte more that one word in string?!

fclose( pekaFile );
}
printf("Command me: "); //<<<== gets printed 2 times, why?
cQuit = cKommando;
cK = getchar();
cKommando = (char)cK;
}
}/* END main */

/* BEGIN new.c */

#include <stdio.h>
#include <stdlib.h>

#define a_LEN 79
#define s_LEN 79
#define str(x) # x
#define xstr(x) str(x)

int main(void)
{
char a_Namn[a_LEN + 1], s_Namn[s_LEN + 1];
int cK, rc;
FILE *pekaFile;

puts("l - for read file");
puts("s - for writte file");
puts("q - quite");
fputs("Command me: ", stdout);
fflush(stdout);
cK = getchar();
getchar();
while (cK != 'q') {
if (cK == 'l' || cK == 'L') {
pekaFile = fopen("registre t.txt", "r");
if (pekaFile == NULL) {
puts("Can't open file");
exit(EXIT_FAILU RE);
}
puts("\nCD register\n");
puts("a_ NAMN");
do {
cK = fgetc(pekaFile) ;
putchar(cK);
} while (cK != EOF);
fclose(pekaFile );
putchar('\n');
} else {
if (cK == 's' || cK == 'S') {
fputs("Type a name: ", stdout);
fflush(stdout);
rc = scanf("%" xstr(a_LEN) "[^\n]%*[^\n]", a_Namn);
if (!feof(stdin)) {
getchar();
}
if (rc != 1) {
*a_Namn = '\0';
}
fputs("Type cd titel: ", stdout);
rc = scanf("%" xstr(s_LEN) "[^\n]%*[^\n]", s_Namn);
if (!feof(stdin)) {
getchar();
}
if (rc != 1) {
*s_Namn = '\0';
}
pekaFile = fopen("registre t.txt","a");
if (pekaFile == NULL) {
fputs("Can't open file \n", stderr);
exit(EXIT_FAILU RE);
}
fprintf(pekaFil e, "%s %s\n", a_Namn, s_Namn);
fclose(pekaFile );
}
}
fputs("Command me: ", stdout);
fflush(stdout);
cK = getchar();
getchar();
}
return 0;
}

/* END new.c */
--
pete

[pete]

pete wrote:

puts("a_ NAMN");

Should be:

puts("ARTIST NAMN");

--
pete

[Carramba]

oh man thats rocks! thanx, I jus have few questions and I hope you don't
mind to answer them

On Tue, 07 Jun 2005 23:04:11 +0200, pete <pf*****@mindsp ring.com> wrote:

/* BEGIN new.c */
#include <stdio.h>
#include <stdlib.h>
#define a_LEN 79
#define s_LEN 79
#define str(x) # x <= what is it? and why?
#define xstr(x) str(x) <= what is it? and why?
int main(void)
{
char a_Namn[a_LEN + 1], s_Namn[s_LEN + 1];
int cK, rc;
FILE *pekaFile;
puts("l - for read file");
puts("s - for writte file");
puts("q - quite");
fputs("Command me: ", stdout);
fflush(stdout);
cK = getchar();
getchar(); why do you double getchar(); ?
while (cK != 'q') {
if (cK == 'l' || cK == 'L') {
pekaFile = fopen("registre t.txt", "r");
if (pekaFile == NULL) {
puts("Can't open file");
exit(EXIT_FAILU RE);
}
puts("\nCD register\n");
puts("a_ NAMN");
do {
cK = fgetc(pekaFile) ;
putchar(cK);
} while (cK != EOF);
fclose(pekaFile );
putchar('\n');
} else {
if (cK == 's' || cK == 'S') {
fputs("Type a name: ", stdout);
fflush(stdout);
rc = scanf("%" xstr(a_LEN) "[^\n]%*[^\n]", a_Namn);
don't realy understand what are you doing here ( in line above )? I se
that you are reading input, but could you explaine more?
if (!feof(stdin)) {
getchar();
}
if (rc != 1) {
*a_Namn = '\0';
}
fputs("Type cd titel: ", stdout);
rc = scanf("%" xstr(s_LEN) "[^\n]%*[^\n]", s_Namn);
if (!feof(stdin)) {
getchar();
}
if (rc != 1) {
*s_Namn = '\0';
}
pekaFile = fopen("registre t.txt","a");
here file ll by created if it not exists, is there any reason for error
messege?
if (pekaFile == NULL) {
fputs("Can't open file \n", stderr);
exit(EXIT_FAILU RE);
}
fprintf(pekaFil e, "%s %s\n", a_Namn, s_Namn);
fclose(pekaFile );
}
}
fputs("Command me: ", stdout);
fflush(stdout);
cK = getchar();
getchar();
}
return 0;
}
/* END new.c */

--

Thanx in advance
_______________ _________
BTW. I know my english is not best in the word, so please stop bugging me
about my spelling. And yes Iam sorry you don't understand what I mean, but
there is no point to yell at me. Have a nice day.

[Zoran Cutura]

Carramba <no****@note.co m> wrote:

rc = scanf("%" xstr(a_LEN) "[^\n]%*[^\n]", a_Namn);

don't realy understand what are you doing here ( in line above )? I se
that you are reading input, but could you explaine more?

A line of input is read into the buffer a_Namn.

Notice that a_Namn has a size and you should never write more characters
into a buffer than it can hold. So scanf can be told to at most read a
certain numer of characters. Say if you want to read a word and have a
buffer that can hold 10 characters you'll do something like "%9s". So
scanf will read 9 characters and finish the string with the obligatory
nul-character.
If you don't just want to read a word (a string of characters that
ends at the next white space) you can go for "%[^\n]" which tells scanf
to read any characters that are not newline-characters into the given
buffer. To limit the amount of characters read you can go with
"%99[^\n]" for example. Now this holds teh risc that when you at some
time in development of your program decrease the size fo the buffer from
100 characters to say 50 characters, and don't change the
scanf-format-string to 49 instead of 99, overflow may occure. This is
why many programmers try to calculate the size of the buffers in use
automagically. And also want to do this with scanfs and such.
How could you do this with scanf?
Well as you can see in the above line of code.
a_LEN tells us the size we use literally. Since scanf expects the size
to be passed in a string we need to produce a string of the value a_LEN
represents. The xstr() macro-trick does this.
Now all you need to know ist that in C "strings" " are" " concatenated"
automatically. (So the compiler makes "strings are concatenated" from
the above). I hope this clears up some things.

pekaFile = fopen("registre t.txt","a");

here file ll by created if it not exists, is there any reason for error
messege?

You can't rely on a success of fopen. It may fail for various reasons.

--
Z (zo**********@w eb.de)
"LISP is worth learning for the profound enlightenment experience
you will have when you finally get it; that experience will make you
a better programmer for the rest of your days." -- Eric S. Raymond

[Carramba]

yes thanx got it know, but still have few more questions:
On Tue, 07 Jun 2005 23:04:11 +0200, pete <pf*****@mindsp ring.com> wrote:

/* BEGIN new.c */

#include <stdio.h>
#include <stdlib.h>

#define a_LEN 79
#define s_LEN 79
#define str(x) # x
#define xstr(x) str(x)

int main(void)
{
char a_Namn[a_LEN + 1], s_Namn[s_LEN + 1];
int cK, rc;
FILE *pekaFile;
puts("l - for read file");
puts("s - for writte file");
puts("q - quite");
fputs("Command me: ", stdout);
fflush(stdout);
cK = getchar();
getchar();
while (cK != 'q') {
if (cK == 'l' || cK == 'L') {
pekaFile = fopen("registre t.txt", "r");
if (pekaFile == NULL) {
puts("Can't open file");
exit(EXIT_FAILU RE);
}
puts("\nCD register\n");
puts("a_ NAMN");
do {
cK = fgetc(pekaFile) ;
putchar(cK);
} while (cK != EOF);
fclose(pekaFile );
putchar('\n');
} else {
if (cK == 's' || cK == 'S') {
fputs("Type a name: ", stdout);
fflush(stdout);
rc = scanf("%" xstr(a_LEN) "[^\n]%*[^\n]", a_Namn);
if (!feof(stdin)) {
getchar();
}
what is going on here? if (rc != 1) {
*a_Namn = '\0';
}
do I get it right that the '\0' character ll by atendet to string
a_Namn if input have succedet?
fputs("Type cd titel: ", stdout);
rc = scanf("%" xstr(s_LEN) "[^\n]%*[^\n]", s_Namn);
if (!feof(stdin)) {
getchar();
}
if (rc != 1) {
*s_Namn = '\0';
}
pekaFile = fopen("registre t.txt","a");
if (pekaFile == NULL) {
fputs("Can't open file \n", stderr);
exit(EXIT_FAILU RE);
}
fprintf(pekaFil e, "%s %s\n", a_Namn, s_Namn);
fclose(pekaFile );
}
}
fputs("Command me: ", stdout);
fflush(stdout);
cK = getchar();
getchar();
}
return 0;
}

/* END new.c */

--

Thanx in advance
_______________ _________
BTW. I know my english is not best in the word, so please stop bugging me
about my spelling. And yes Iam sorry you don't understand what I mean, but
there is no point to yell at me. Have a nice day.

[pete]

Carramba wrote:

oh man thats rocks! thanx,
I jus have few questions and I hope you don't
mind to answer them

On Tue, 07 Jun 2005 23:04:11 +0200,
pete <pf*****@mindsp ring.com> wrote:

int cK, rc; cK = getchar(); getchar();

why do you double getchar(); ?

To eat the '\n' from the Enter key.
Note that cK is of type int and not char,
to match the return type of getchar.

fputs("Type a name: ", stdout);
fflush(stdout);
rc = scanf("%" xstr(a_LEN) "[^\n]%*[^\n]", a_Namn);

don't realy understand what are you doing here
( in line above )? I se
that you are reading input, but could you explaine more?

Zorna Cutura explained it pretty good.
The idea, is to convert text lines into strings.
Text files and streams are made of lines.
A line is like a string, except that a line is
teminated by a '\n' character,
and a string is terminated by a '\0' character.

if (!feof(stdin)) {
getchar();
}
if (rc != 1) {
*a_Namn = '\0';
}
fputs("Type cd titel: ", stdout);

There should be
fflush(stdout);
after that fputs.
--
pete

[pete]

Carramba wrote:

#define a_LEN 79 #define str(x) # x
#define xstr(x) str(x) rc = scanf("%" xstr(a_LEN) "[^\n]%*[^\n]", a_Namn);

if (!feof(stdin)) {
getchar();
}
what is going on here?

getchar is eating the '\n' at the end of the text line.
The !feof is a little more complicated to explain,
but it is to also make this work for systems with a
non sticky end of file condition.
I don't really know too much about sticky vs non sticky,
except that systems are supposed to have sticky eof,
but some of them, don't.

if (rc != 1) {
*a_Namn = '\0';
}

do I get it right that the '\0' character ll by atendet to string
a_Namn if input have succedet?

rc is capable of having one of three different values at this point.
If rc equals 1, then there is a string in a_Namn.
If rc equals 0, then that means that the text line
had only a '\n' character and that there is no string in a_Namn.
If rc equals EOF, then you have an end of file condition
or some kind of error, and no string in a_Namn.

--
pete

[pete]

pete wrote:

Zorna

So, I'm thinking to myself "Is Zoran going to notice that?"
and then "Yes, probably."
Sorry about that.

--
pete