Case Expression Not Constant

Expand Post »

When I try to compile this:

c++ Syntax (Toggle Plain Text)
void *BaseEnt::GetVar(char const *varname)
{
	char name = *varname;
	switch(name)
	{
	case "id":
		return (void*)id;
	case "name":
		return (void*)name;
	case "count":
		return (void*)count;
	default:
		return (void*)NULL;
	}
}
void *BaseEnt::GetVar(char const *varname)
{
	char name = *varname;
	switch(name)
	{
	case "id":
		return (void*)id;
	case "name":
		return (void*)name;
	case "count":
		return (void*)count;
	default:
		return (void*)NULL;
	}
}

I get these errors:

C++ Syntax (Toggle Plain Text)
------ Build started: Project: Test Classes, Configuration: Debug Win32 ------
Compiling...
classes.cpp
c:\documents and settings\tom\my documents\visual studio 2008\projects\test classes\test classes\classes.cpp(25) : error C2051: case expression not constant
c:\documents and settings\tom\my documents\visual studio 2008\projects\test classes\test classes\classes.cpp(27) : error C2051: case expression not constant
c:\documents and settings\tom\my documents\visual studio 2008\projects\test classes\test classes\classes.cpp(29) : error C2051: case expression not constant
c:\documents and settings\tom\my documents\visual studio 2008\projects\test classes\test classes\classes.cpp(33) : warning C4065: switch statement contains 'default' but no 'case' labels
Build log was saved at "file://c:\Documents and Settings\tom\My Documents\Visual Studio 2008\Projects\Test Classes\Test Classes\Debug\BuildLog.htm"
Test Classes - 3 error(s), 1 warning(s)
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========
------ Build started: Project: Test Classes, Configuration: Debug Win32 ------
Compiling...
classes.cpp
c:\documents and settings\tom\my documents\visual studio 2008\projects\test classes\test classes\classes.cpp(25) : error C2051: case expression not constant
c:\documents and settings\tom\my documents\visual studio 2008\projects\test classes\test classes\classes.cpp(27) : error C2051: case expression not constant
c:\documents and settings\tom\my documents\visual studio 2008\projects\test classes\test classes\classes.cpp(29) : error C2051: case expression not constant
c:\documents and settings\tom\my documents\visual studio 2008\projects\test classes\test classes\classes.cpp(33) : warning C4065: switch statement contains 'default' but no 'case' labels
Build log was saved at "file://c:\Documents and Settings\tom\My Documents\Visual Studio 2008\Projects\Test Classes\Test Classes\Debug\BuildLog.htm"
Test Classes - 3 error(s), 1 warning(s)
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

I thought that things like "id" were constant because they're a litteral?

Any help would be appreciated.

PS. If you need more information on my problem, feel free to ask.

Similar Threads

Time complexity of algorithm in Computer Science
put a struct type val in a FILE in C
Linker Error in C++
Problem with inheritance in C++

tomtetlaw

Reputation Points: 9

Solved Threads: 5

Posting Pro

Offline

591 posts
since Sep 2008

Permalink

Nov 2nd, 2009

Re: Case Expression Not Constant

the param to a switch cannot be a string.
It can only be an integer. To achieve what u are trying use if-else statement alongwith strcmp().

dkalita

Reputation Points: 121

Solved Threads: 61

Posting Pro in Training

Offline

402 posts
since Sep 2009

Permalink

Nov 2nd, 2009

-2

Re: Case Expression Not Constant

try this

c++ Syntax (Toggle Plain Text)
void *BaseEnt::GetVar(char const *varname)
{
	char name = *varname;
	switch(name)
	{
	case 'id':                        //use ' not "
		return (void*)id;
	case 'name':                       //use ' not "
		return (void*)name;
	case 'count':                       //use ' not "  
		return (void*)count;
	default:
		return (void*)NULL;
	}
}
void *BaseEnt::GetVar(char const *varname)
{
	char name = *varname;
	switch(name)
	{
	case 'id':                        //use ' not "
		return (void*)id;
	case 'name':                       //use ' not "
		return (void*)name;
	case 'count':                       //use ' not "  
		return (void*)count;
	default:
		return (void*)NULL;
	}
}

slackingjuggalo

Reputation Points: 8

Solved Threads: 0

Newbie Poster

Offline

1 posts
since Nov 2009

This thread is more than three months old

No one has posted to this discussion for at least three months. Please let old threads die and do not reply to them unless you feel you have something new and valuable to contribute that absolutely must be added to make the discussion complete. Otherwise, please start a new thread in this forum instead.

Previous Thread in C++ Forum Timeline: Why is C++ so big?

Next Thread in C++ Forum Timeline: LPD3DXMESH vs ID3DXMesh

DaniWeb Message

Cancel Changes

User Name
Password