clearing a used array

[smegly]

Hi,

is there a way to re-initilise an array to allow it to be empty again ..

this is what i have done, but my output, doesnt clear it..

for(j=0; j<MAX_LEN; j++)
       { 
          buff[j] = ' '; //flush the strings. .
          printf("buff[%c] - buff", buff[j]);
       }

this is my output, from file

Customer No: Fri May 21 23:58:09 2004

Customer 100: deposit

Arrival time: Fri May 21 23:58:09 2004

Customer 2112 : deposit

Arrival time: Fri May 21 23:58:09 2004

Customer 3112 : withdraw

Arrival time: Fri May 21 23:58:09 2004

Customer 4112 : deposit

Arrival time: Fri May 21 23:58:09 2004

Customer 5112 : withdraw

Arrival time: Fri May 21 23:58:09 2004

the input is

100 deposit
2112 deposit
3 withdraw
4 deposit
5 withdraw

so basically 3112 is from the old inputs . .

Please help

Matt

[chrismiceli]

Dont know about your inputs, but the output of you code snippet should be this
"buff[ ] - buff"
until MAX_LEN is met.

[loopy]

#include <stdio.h>
#include <strings.h>

int main()
{
	char buf[1024] = "Hello, full string here!";
  	fprintf(stdout, "%s\nGive Me Input!!\n", buf);
        buf[0] = '\0';
	if (fgets(buf, sizeof(buf), stdin) == NULL) {
		fprintf(stderr, "fgets: Failed.\n");
		return 1;
	}
	fprintf(stdout, "Your new string is: %s\n", buf);
	return 0;
}

Just null terminate the first element. : )

[quzah]

memset( array, 0, arraysize );

[edit]*slaps forehead*[/edit]

Quzah.

[loopy]

Do you even NEED to clear an array? It seems to work to just write over it...

[smegly]

ok this is my function at the moment ..

I still cannot get it to clear the buffer correctly . .

    while (fgets(buff, MAX_LEN, fin) != NULL)

    {

       char custAction[MAX_LEN];
       char custRef[MAX_LEN];      

       int i=0;
       int x=0;

       while((buff[i] != ' ') && (i <= MAX_LEN))
       { //read from buffer storing in custRef values up till
         //a ' ' is found

         custRef[i] = buff[i];
           i++;
       }

       i++; //increment i past the space

       while((buff[i] != ' ') && (i <=MAX_LEN) && (buff != NULL))
       { //read the rest of buffer till next space or EOF
           custAction[x] = buff[i];
          
           i++;
	   x++;
       }

       //printf("custAction is equal to -  %s\n", custAction);   
       
       
                    
       //for(j=0; j<MAX_LEN; j++)
       //{ 
       //   buff[j] = ' '; //flush the strings. .
       //}

       memset(buff, 0, MAX_LEN); //reset buffer

       printf("%s/n", buff);
       time(&now);

       fprintf(fout,"Customer %s: %s\nArrival time: %s\n", custRef, custAction, ctime(&now));
       sleep(2);
    }

i'm using the memset correctly .. so i figure it is in the wrong spot.. but i cannot find where it should be placed..

Matt

[linuxdude]

buff != NULL

should be buff[i]!='\0'

{ //read the rest of buffer till next space or EOF

It isn't EOF it is NULL you even wrote it there. \0 is the string version of NULL. Everything else seems fine, save the one line comments

[smegly]

buff != NULL

should be buff[i]!='\0'

{ //read the rest of buffer till next space or EOF

It isn't EOF it is NULL you even wrote it there. \0 is the string version of NULL. Everything else seems fine, save the one line comments

But this still does not solve the problem of my buffer..

I am still getting reminents of the old custRef on the next pass ..

[quzah]

Everything else seems fine, save the one line comments

Not quite.

while((buff[i] != ' ') && (i <= MAX_LEN))

That's wrong. If i is MAX_LEN, then it is beyond the end of the buffer, which is a BadThingTM.

Additionally...

 while((buff[i] != ' ') && (i <=MAX_LEN) && (buff != NULL))

Should be...

 while((buff[i] != ' ') && (i <=MAX_LEN) && (buff[i] != NULL))

Because... "buff" never changes. It is always considered a pointer to the first element of the array. As such, since it is an array that by definition always exists, even if you have the value of buff[0] as zero (NULL), the array itself, and as a result, the pointer to its first element will still never be NULL.

Also...

printf("%s/n", buff);

Your backslash has fallen over on its face.

Quzah.
[edit]fixed color tag[/edit]

[smegly]

I solved the problem . .

I needed to clear custRef as well as buff..

so i print to the file and then clear the buffer.. works a treat now ..

On to my next problem.. Msgget and semaphores . .

ARGHH!!

[linuxdude]

Arg I caught the buff[i] prob but I glanced over the = so sue me