# Can modify array during iteration

**URL:** <https://www.ruby-forum.com/t/can-modify-array-during-iteration/126935>\
**Category:** Development\
**Created:** [January 23, 2008, 4:03pm UTC](https://www.ruby-forum.com/t/can-modify-array-during-iteration/126935 "2008-01-23T16:03:50Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![Yusuke\_ENDOH](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/y/c89c15/32.png) [@Yusuke\_ENDOH](https://www.ruby-forum.com/u/Yusuke_ENDOH)\
**Post date:** [January 23, 2008, 4:03pm UTC](https://www.ruby-forum.com/t/can-modify-array-during-iteration/126935/1 "2008-01-23T16:03:50Z")

</div>

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a = [0, 1, 2]  
a.each do  
a.each {}  
a.clear  
end  
p a #=\> []

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$ ./ruby -e ’  
a = (0 … 100000).to\_a  
a.map! do |i|  
if i == 99999  
a.each { }  
a.clear  
end  
i  
end  
’  
-e:3: [BUG] Segmentation fault  
ruby 1.9.0 (2008-01-23 revision 0) [i686-linux]

## – control frame ---------- c:0004 p:---- s:0010 b:0010 l:000009 d:000009 CFUNC :map! c:0003 p:0018 s:0007 b:0007 l:000006 d:000006 TOP -e:3 c:0002 p:---- s:0004 b:0004 l:000003 d:000003 FINISH :inherited c:0001 p:0000 s:0002 b:0002 l:000001 d:000001 TOP :17

## DBG\> : “-e:3:in `’” – backtrace of native function call (Use addr2line) – 0x80f04a5 0x810f3ce 0x810f42b 0x80bf860 0xffffe440 0x80598b1 0x80fabf5 0x80eecc3 0x80ea5ee 0x80edeb4 0x80ee1ed 0x805a6f9 0x805e840 0x8058121 0xb7dc1ea8 0x8058031

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# Index: array.c

— array.c (revision 15191)  
+++ array.c (working copy)  
@@ -1644,7 +1644,7 @@

```
 rb_ary_modify(ary);
 for (i = 0; i < RARRAY_LEN(ary); i++) {

```

- RARRAY\_PTR(ary)[i] = rb\_yield(RARRAY\_PTR(ary)[i]);

- rb\_ary\_store(ary, i, rb\_yield(RARRAY\_PTR(ary)[i]));  
}  
return ary;  
}

---

<div class="post-metadata">

**Author:** ![Yusuke\_ENDOH](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/y/c89c15/32.png) [@Yusuke\_ENDOH](https://www.ruby-forum.com/u/Yusuke_ENDOH)\
**Post date:** [January 24, 2008, 5:06am UTC](https://www.ruby-forum.com/t/can-modify-array-during-iteration/126935/2 "2008-01-24T05:06:54Z")

</div>

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At Thu, 24 Jan 2008 00:03:24 +0900,  
Yusuke ENDOH wrote in [ruby-dev:33328]:

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> e$B$^$9!#e(B

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> e$B=q$-49$($i$l$J$$$3$H$rA0Ds$K$7$F$$$k$3$H$,860x$G$9!#e(B

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---

<div class="post-metadata">

**Author:** ![Yusuke\_ENDOH](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/y/c89c15/32.png) [@Yusuke\_ENDOH](https://www.ruby-forum.com/u/Yusuke_ENDOH)\
**Post date:** [January 24, 2008, 7:02am UTC](https://www.ruby-forum.com/t/can-modify-array-during-iteration/126935/3 "2008-01-24T07:02:02Z")

</div>

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In message “Re: [ruby-dev:33343] Re: can modify array during iteration”  
on Thu, 24 Jan 2008 13:05:43 +0900, Nobuyoshi N.  
[removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) writes:

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