CODEWITHSUNDEEP
carrayscommandargumentsstorage
Simple Boy
Simple Boy

Reputation: 39

Can't store arguments as arrays and print them in C

I have the program (let's call it pr), and I can't understand what happens that suddenly I get an error when everything seem to be right. In terminal, I type:

./pr 2011-11-01/03:20

and I want to store into 2 arrays the date and the time. The date in the array aa == "2011-11-01" and the time in bb == "03:20" and at the end print them. So, I wrote the code below:

EDIT: The new code with malloc() below:

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

int main (int argc, char *argv[]) {
int j=0, i=0;
char *aa = malloc(10*sizeof(char));
char *bb = malloc(5*sizeof(char));

while ( j!=10 ) {
    aa[j] = *(argv[1]+j);
j++;
}
j++;
while ( *(argv[1]+j) != '\0' ) {
    bb[j-11] = *(argv[6]+j++);
}
printf("%s and %s", aa, bb);
}

But the output of the above is:2011-11-01Y and 03:20 where Y is a random character every time...

End of edit...

Old one below:

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

int main (int argc, char *argv[])
{
    char *aa, *bb; int j=0, i=0;
    while ( *(argv[1]+j) != '/' )
    {
        aa[j] = *(argv[6]+j++);
    }
    j++;

    while ( *(argv[1]+j) != '\0' )
    {
        bb[i++] = *(argv[1]+j++);
    }
    printf("%s %s", aa, bb);
}

The code above doesn't work for some reason, but when I write:

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

int main (int argc, char *argv[])
{
    char *aa; int j=0;
    while ( *(argv[1]+j) != '/' )
    {
        aa[j] = *(argv[1]+j++);
    }
    printf("%s", aa);
}

or

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

int main (int argc, char *argv[])
{
    char *bb; int j, i=0;
    j=11; printf("%d", j);
    while ( *(argv[1]+j) != '\0' )
    {
        bb[i++] = *(argv[1]+j++);
    }
    printf("%s", bb);
}

it works fine! Does anybody know why is this happening?

Upvotes: 0

Views: 82

Answers (1)

zbs
zbs

Reputation: 681

You should do

char *aa = malloc(11*sizeof(char));

to account for the \0 character and after the first loop you should write

aa[j] = '\0'

Basically, you are not ending the aa string with a \0 so the printf does not stop at the final character and thus you have a random one afterwards.

Upvotes: 1

Related Questions