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digitalmars.D - Bus error accessing char [] by index - OS X

reply Cam MacRae <cam.macrae gmail.com> writes:
Executing the following example program compiled with

 gdc stringtest.d -o stringtest

I get a bus error on OS X accessing the char array by index (shown in the comments below). I imagine this might be a gdc on OS X issue - any other ideas? import std.stdio; void main() { char[] firstname firstname = "Cam"; char [] a = firstname, b = firstname; a[0] = 'H'; //Bus error here writefln(b); } cheers, Cam.
Nov 06 2007
parent reply BCS <ao pathlink.com> writes:
Reply to Cam,

 Executing the following example program compiled with
 
 gdc stringtest.d -o stringtest
 

the comments below). I imagine this might be a gdc on OS X issue - any other ideas? import std.stdio; void main() { char[] firstname firstname = "Cam"; char [] a = firstname, b = firstname; a[0] = 'H'; //Bus error here writefln(b); } cheers, Cam.

On linux, string literals are in read only memory space. As for OS X...???
Nov 06 2007
parent reply Cam MacRae <cam.macrae gmail.com> writes:
BCS Wrote:

 Reply to Cam,
 
 
 On linux, string literals are in read only memory space. As for OS X...???
 
 

Thanks mate - that could be it. I was just following along the D Transition guide (http://en.wikibooks.org/wiki/D_Transition_Guide). Perhaps it's out of date... c.
Nov 06 2007
parent reply Regan Heath <regan netmail.co.nz> writes:
Cam MacRae wrote:
 BCS Wrote:
 
 Reply to Cam,
 
 
 On linux, string literals are in read only memory space. As for OS
 X...???
 
 

Thanks mate - that could be it. I was just following along the D Transition guide (http://en.wikibooks.org/wiki/D_Transition_Guide). Perhaps it's out of date...

More like "windows centric" as string literals can be written to on windows. Simple fix: char[] a = firstname.dup, b = firstname; a[0] = 'H'; //5 but perhaps dup needs to be introduced or explained before being used here... Regan
Nov 07 2007
parent reply Regan Heath <regan netmail.co.nz> writes:
Regan Heath wrote:
 Cam MacRae wrote:
 BCS Wrote:

 Reply to Cam,


 On linux, string literals are in read only memory space. As for OS
 X...???

Thanks mate - that could be it. I was just following along the D Transition guide (http://en.wikibooks.org/wiki/D_Transition_Guide). Perhaps it's out of date...

More like "windows centric" as string literals can be written to on windows. Simple fix: char[] a = firstname.dup, b = firstname; a[0] = 'H'; //5

Actually, this breaks the example entirely as b is no longer modified by a[0] - 'H' oops. Regan
Nov 07 2007
parent Regan Heath <regan netmail.co.nz> writes:
Regan Heath wrote:
 Regan Heath wrote:
 Cam MacRae wrote:
 BCS Wrote:

 Reply to Cam,


 On linux, string literals are in read only memory space. As for OS
 X...???

Thanks mate - that could be it. I was just following along the D Transition guide (http://en.wikibooks.org/wiki/D_Transition_Guide). Perhaps it's out of date...

More like "windows centric" as string literals can be written to on windows. Simple fix: char[] a = firstname.dup, b = firstname; a[0] = 'H'; //5

Actually, this breaks the example entirely as b is no longer modified by a[0] - 'H' oops.

Here is my suggested fix - I don't have DMD 1.0 to test this with so someone else is going to have to edit the wiki (after testing this works!) import std.stdio; void main() { char[] firstname, lastname, fullname; //1 firstname = "Walter".dup; //2 lastname = "Bright"; //3 fullname = firstname ~ " " ~ lastname; //4 writefln("Congratulations on making a great language " ~ fullname); //5 char[] a = firstname, b = firstname; a[0] = 'H'; //6 writefln(b); //prints "Halter" writefln("Your name is still %s, right?", fullname); //7, prints Walter Bright } 1. Strings are nothing more than character arrays. You'll see more about arrays later, but for now, know that character arrays are not a special case. The one major note is that D strings are not null terminated. Arrays simply keep track of their length. 2. dup used here to create a copy of the string "Walter" (this is because string literals are read-only on some OS's) 3. No strcpy here. In fact, this is more like reassigning a pointer (ie, char *lastname = "Bright"). 4. ~ is the concatenation operator. There is no ambiguity between + and ~ for strings. 5. One way of outputting, although number 7 is better 6. Since a is really a pointer to firstname, firstname (and hence b) actually get modified on this line. 7. But since fullname was created through concatenation, it remains unchanged.
Nov 07 2007