. NET Framework 4 compatibility issues

Test Program

Let's take a look at the very simple C # program tester. CS below:

 1   Using  System;  2   3   Static   Class  Tester  4   {  5     Static   Void  Main ()  6  {  7 Console. writeline ( "  CLR:  " + Environment. version );  8 Console. writeline ( "  Concat:  " + String . Concat ( New   Int [] { 12 , 345 }));  9   }  10 }

The actual content of this test program is only one row, that is, 8th rows. The static method Concat of the string class is called.

Running result

Let's take a look at the running results of the above test program. The first is the mono environment of the Linux operating system:

 
Ben @ vbox :~ /Work>GMCs tester. CS & mono tester.exeCLR: 2.0.50727.1433concat:System. int32 []Ben @ vbox :~ /Work>DMCS tester. CS & mono tester.exeCLR: 4.0.30319.1concat:12345
 

Microsoft. NET Framework environment for Windows:

D: \ work>C: \ windows \ Microsoft. NET \ framework \ v2.0.50727 \ csc.exe tester. CSMicrosoft (r) Visual C #2005 compiler version 8.00.50727.4016 is used for Microsoft (r) Windows (r) 2005 Framework Version 2.0.50727 copyright (c) Microsoft Corporation 2001-2005. All rights reserved. D: \ work>Tester.exeCLR: 2.0.50727.4216concat:System. int32 []D: \ work>C: \ windows \ Microsoft. NET \ framework \ v4.0.30319 \ csc.exe tester. CSMicrosoft (r) Visual C #2010 compiler 4.0.30319.1 copyright (c) Microsoft Corporation. All rights reserved. D: \ work>Tester.exeCLR: 4.0.30319.276concat:12345
 

As you can see, the same C # program, whether it is a Linux operating system or a Windows operating system, shows incompatibility between. NET Framework 2.0 and. NET Framework 4.

Analysis

The above running result is mainly because the static method Concat of the string class has nine overloaded versions in. NET Framework 2.0, and there are 11 overloaded versions in. NET Framework 4. The actual version of the C # program called for the above test is as follows:

. NET Framework 2.0: public static string Concat (Object arg0). Net Framework 4: Public static string Concat <t> (ienumerable <t> values)
 

It seems that adding new methods to the. NET Framework base class library is not safe, and may change the behavior of the original C # program. This reminds us to extract the original program from. net Framework 2.0. NET framework 4 should be careful during migration, not only to note that the "version considerations" are clearly stated in msdn, but also to pay attention to this subtle change.

View Il Code

Run the following command in Linux to decompile tester.exe as ilasm.Source codeFile:

 
Ben @ vbox :~ /Work>GMCs tester. CS & monodis tester.exe> Tester-v2.ilBen @ vbox :~ /Work>DMCS tester. CS & monodis tester.exe> Tester-v4.il
 

Below is the Tester-v2.il file:

 1   . Assembly  Extern  Mscorlib  2   {  3     . Ver   2 : 0 : 0 : 0  4     . Publickeytoken = (B7 7A 5C 56   19   34 E0 89 )//  . Z \ v.4 ..  5   }  6   . Assembly   '  Tester  '  7   {  8     . Custom   Instance   Void   Class [Mscorlib] system. runtime. compilerservices. runtimecompatibilityattribute ::'  . Ctor  '  () = (  9                   01   00   01   00   54   02   16   57   72   61   70 4e 6f 6e 45   78    //  ... T... wrapnonex  10                   63   65   70   74   69 6f 6e 54   68   72 6f 77   73   01 ) //  Ceptionthrows.  11  12     . Hash   Algorithm   Zero X 00008004  13     . Ver    0 : 0 : 0 : 0  14   }  15   . Module Tester.exe //  Guid = {9f6a8c8f-b962-4e6a-a4e9-fa6ff9e83982} 16   17   18     . Class   Private   Auto   ANSI Abstract sealed Beforefieldinit  Tester  19           Extends  [Mscorlib] system. Object  20   {  21   22       // Method Line 1  23       . Method   Private Static Hidebysig  24 Default Void Main () Cel   Managed  25   {  26           //  Method begins at RVA 0x20ec  27          . Entrypoint  28           //  Code size 60 (0x3c)  29           . Maxstack   8  30           Il_0000:    Ldstr   "  CLR:  "  31           Il_0005:    Call   Class [Mscorlib] system. Version Class  [Mscorlib] system. Environment: get_version ()  32           Il_000a:    Call   String   String : Concat ( Object , Object  )  33           Il_000f:    Call   Void   Class [Mscorlib] system. Console: writeline ( String  )  34           Il_0014:    Ldstr   "  Concat:  "  35           Il_0019:    LDC. i4.2  36           Il_001a:    Newarr  [Mscorlib] system. int32  37          Il_001f:    DUP  38           Il_0020:    LDC. i4.0  39           Il_0021:    LDC. i4.s   0x0c  40           Il_0023:    Stelem. I4  41           Il_0024:    DUP  42           Il_0025:   LDC. i4.1  43           Il_0026:    LDC. I4   345  44           Il_002b:    Stelem. I4  45           Il_002c:    Call   String   String : Concat ( Object  )  46           Il_0031:   Call   String   String : Concat ( String , String  )  47           Il_0036:    Call   Void   Class [Mscorlib] system. Console: writeline ( String  )  48           Il_003b:    RET 49 } //  End of method Tester: Main  50   51 } //  End of class Tester 

Use the diff command to look at the differences between Tester-v4.il and Tester-v2.il:

Ben @ vbox :~ /Work>Diff Tester-v2.il Tester-v4.il3c3<. Ver2: 0: 0: 0--->. Ver4: 0: 0: 015c15<. Module tester.exe // guid = {9f6a8c8f-b962-4e6a-a4e9-fa6ff9e83982} --->. Module tester.exe // guid = {D564CE72-73D3-43DD-B6F4-FB12809D5589}45c45<Il_002c: Call string: Concat (Object) ---> Il_002c: Call string: Concat<Int32>(Class [mscorlib] system. Collections. Generic. ienumerable '1 <!! 0>)
 

We can see that there are only three differences in total:

1. Different lines 3rd indicate different. NET Framework versions.
2. The differences in rows 15th only indicate that different tester.exe guids are different.
3. The differences in row 45th indicate that the overloaded version of the called Concat method is different.

The differences between the above 3rd points validate our analysis in the previous section and clearly show the different overloaded versions of the Concat method called accordingly.

References

1. Msdn: String. Concat method (system)
2. Msdn: String. Concat method (object) (system)
3. Msdn: String. Concat (t) method (ienumerable (t) (system)