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digitalmars.D - weird empty string

reply mogu <mogucpp 163.com> writes:
```d
if (null)
     "1".writeln;
if ("")
     "2".writeln;
if ("" == null)
     "3".writeln;
```

Output:
2
3

How to understand this?
May 12
parent reply Stanislav Blinov <stanislav.blinov gmail.com> writes:
On Saturday, 13 May 2017 at 00:36:55 UTC, mogu wrote:
 ```d
 if (null)
     "1".writeln;
 if ("")
     "2".writeln;
 if ("" == null)
     "3".writeln;
 ```

 Output:
 2
 3

 How to understand this?
Boolean conversion on an array works on array's pointer, not it's length. So even though `"".length == 0`, `"".ptr != null`, and so `cast(bool)"" == true`.
May 12
next sibling parent reply mogu <mogucpp 163.com> writes:
On Saturday, 13 May 2017 at 00:59:14 UTC, Stanislav Blinov wrote:
 On Saturday, 13 May 2017 at 00:36:55 UTC, mogu wrote:
 ```d
 if (null)
     "1".writeln;
 if ("")
     "2".writeln;
 if ("" == null)
     "3".writeln;
 ```

 Output:
 2
 3

 How to understand this?
Boolean conversion on an array works on array's pointer, not it's length. So even though `"".length == 0`, `"".ptr != null`, and so `cast(bool)"" == true`.
```d string s1 = null; string s2 = ""; assert(s1 == null); assert(s1.ptr == null); assert(s2 == null); assert(s2.ptr != null); if (s1) 1.writeln; if (s2) 2.writeln; ``` Output: 2 Thanks very much. This is a little bit confusing.
May 12
parent Kagamin <spam here.lot> writes:
On Saturday, 13 May 2017 at 03:41:29 UTC, mogu wrote:
 Thanks very much. This is a little bit confusing.
There was a lot of discussion about it: https://issues.dlang.org/show_bug.cgi?id=4733, https://forum.dlang.org/thread/rrrtkfosfnfuybblexow forum.dlang.org
May 14
prev sibling parent reply Yuxuan Shui <yshuiv7 gmail.com> writes:
On Saturday, 13 May 2017 at 00:59:14 UTC, Stanislav Blinov wrote:
 On Saturday, 13 May 2017 at 00:36:55 UTC, mogu wrote:
 ```d
 if (null)
     "1".writeln;
 if ("")
     "2".writeln;
 if ("" == null)
     "3".writeln;
 ```

 Output:
 2
 3

 How to understand this?
Boolean conversion on an array works on array's pointer, not it's length. So even though `"".length == 0`, `"".ptr != null`, and so `cast(bool)"" == true`.
However if ([]) "1".writeln; prints nothing. So why does "" has non-null pointer while [] has null pointer? Looks inconsistent.
May 12
parent ag0aep6g <anonymous example.com> writes:
On 05/13/2017 06:20 AM, Yuxuan Shui wrote:
 So why does "" has non-null pointer while [] has null pointer? Looks
 inconsistent.
String literals are null-terminated, so "" needs to point at a null byte.
May 12