How can I replace a new line character with a null terminator?

Question

My program is a task list manager... it takes the name, priority, and date of a task using fgets/stdin and puts it in a struct. This is the relevant snippet of my program:

task *makeTask(char *name, char *date, char *priority)
{

        task *the_task = malloc(sizeof(task));

        int i;

        the_task->task_name = (char*)malloc(sizeof(char) * (strlen(name)));

         for (i=0;name[i] != '\n'; i++) {
                if (name[i] != '\0')
                the_task->task_name[i] = name[i];
        }

        the_task->task_name[i] = '\0';

        //already allocated for in struct
        for (i=0;date[i] != '\n'; i++) {
                if (date[i] != '\0')
                the_task->date_entered[i] = date[i];
        }

        the_task->date_entered[i] = '\0';


        the_task->priority = atoi(priority);
        return the_task; // FILE THIS IN
}

Here's the expected output:

0: Feed the cats, priority: 5.  Entered 01/01/1111

And here's the actual output:

0: edsats, priority: 5.  Entered 01/01/1111

I've been scratching my head for the past hour trying to fix this problem... what's going on with my code?

Hah, I'm innocent of that, honestly. My TA said I needed to future-proof my code for the next two decades. =/ — user1787531, Apr 17 '13 at 03:15
That's not future-proofing. Rather, it's making your code less maintainable and more error-prone. — R.. GitHub STOP HELPING ICE, Apr 17 '13 at 03:30
`malloc(sizeof(char) * (strlen(name)))`. Realize you don't have enough space to store the null pointer. — quantum, Apr 17 '13 at 03:39
R is complaining because `sizeof(char)` is guaranteed to be 1. Also, I would probably write `sizeof(the_task->task_name[0])` if I were worried about future proofing. — Timothy Jones, Apr 17 '13 at 03:50
Also, it's best not to include the cast in front of the malloc - see http://stackoverflow.com/questions/1565496/specifically-whats-dangerous-about-casting-the-result-of-malloc — Timothy Jones, Apr 17 '13 at 03:54

score 1 · Accepted Answer · answered Apr 17 '13 at 02:49

1

I would suggest a couple of things:

You need an extra byte to store the task name, to hold the null terminator
use strdup to allocate memory for a string and copy it into it (for the task name)
use strcpy to copy the date into its preallocated string

I'm also uncertain if you're showing us the code that is actually causing the problem, but try fixing the task name memory block to see if that helps.

answered Apr 17 '13 at 02:49

lxop

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Excellent suggestions, lxop. The code is cleaner and functioning properly now. Much obliged. – user1787531 Apr 17 '13 at 03:48

score 1 · Answer 2 · answered Apr 17 '13 at 02:49

1

You don't allocate space for the_task->date_entered.
You need to add strlen(name) + 1 bytes to account for the null terminator.

answered Apr 17 '13 at 02:49

John Kugelman

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How can I replace a new line character with a null terminator?

2 Answers2