Databases
StackOverflow2013
Postsdbo
POstrcpy valgrind invalid read of size
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POstrcpy valgrind invalid read of size
    primarykey
    data
    text
    <blockquote> <p><strong>Possible Duplicate:</strong><br> <a href="https://stackoverflow.com/questions/7997379/the-valgrind-reports-error-when-printing-allocated-strings">The valgrind reports error when printing allocated strings</a> </p> </blockquote> <p>I have code which simply copies string. I remember to allocate memory, but valgrind shows some errors and I don't understand this.</p> <pre><code>#include &lt;stdio.h&gt; #include &lt;stdlib.h&gt; #include &lt;string.h&gt; typedef struct foo { char *a; }; struct foo* create(char *lol){ struct foo *test = malloc(sizeof(struct foo)); test-&gt;a = malloc(sizeof(char) * (strlen(lol)+1)); strcpy(test-&gt;a, lol); return test; } int main() { char *a = malloc(5*sizeof(char)); strcpy(a, "test"); struct foo *c = create("test"); printf("%s\n%s\n", a, c-&gt;a); printf("%s\n", c-&gt;a); free(a); free(c-&gt;a); free(c); return 0; } </code></pre> <p>Gives valgrind output:</p> <pre><code>==13825== Memcheck, a memory error detector ==13825== Copyright (C) 2002-2011, and GNU GPL'd, by Julian Seward et al. ==13825== Using Valgrind-3.7.0 and LibVEX; rerun with -h for copyright info ==13825== Command: ./a.out ==13825== test test ==13825== Invalid read of size 4 ==13825== at 0x40C301B: ??? (in /lib/libc-2.14.1.so) ==13825== by 0x4066242: (below main) (in /lib/libc-2.14.1.so) ==13825== Address 0x41ca09c is 4 bytes inside a block of size 5 alloc'd ==13825== at 0x402A018: malloc (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so) ==13825== by 0x80484F3: create (in /home/patseb/src/mgr/test/a.out) ==13825== by 0x8048550: main (in /home/patseb/src/mgr/test/a.out) ==13825== test ==13825== ==13825== HEAP SUMMARY: ==13825== in use at exit: 0 bytes in 0 blocks ==13825== total heap usage: 3 allocs, 3 frees, 14 bytes allocated ==13825== ==13825== All heap blocks were freed -- no leaks are possible ==13825== ==13825== For counts of detected and suppressed errors, rerun with: -v ==13825== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 13 from 8) </code></pre> <p>I didn't get why error is not occuring before first printf();</p>
    singulars
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PTQuestion
    1. USCommunity
    1. USpatseb
    plurals
    1. PL
      singulars
      1. LTLinked
    2. PL
      singulars
      1. LTDuplicate
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. VO
      singulars
      1. POstrcpy valgrind invalid read of size
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. POstrcpy valgrind invalid read of size
      1. This table or related slice is empty.
      1. VTApproveEditSuggestion
    3. VO
      singulars
      1. POstrcpy valgrind invalid read of size
      1. This table or related slice is empty.
      1. VTUpMod
    1. COJust a little advice: use `strdup` instead of `malloc`ing and `strcpy`ing the string.
      singulars
      1. POstrcpy valgrind invalid read of size
      1. USConstantinius
    2. COIt's a bug. See [this thread](http://stackoverflow.com/questions/7997379/the-valgrind-reports-error-when-printing-allocated-strings). Change `printf("%s\n", c->a);` to `printf("%s \n", c->a);` and you'll make it go away.
      singulars
      1. POstrcpy valgrind invalid read of size
      1. UScnicutar
    3. CONo need to use `* sizeof(char)`. From the K&R: "_When sizeof is applied to a char, the result is 1;_"
      singulars
      1. POstrcpy valgrind invalid read of size
      1. UScalandoa
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload