Strange behavior of ROOT/CINT with function RemoveSubString(

ROOT
1

Dear Rooters

I have written the following function to remove a substring:
TString RemoveSubString(const char *name, const char *substr)
{
TString outname = TString(name);
char *tmpname = new char[strlen(name) + 1];
char *delname = tmpname;
Int_t len = 0;
char *pos;

tmpname = strcpy(tmpname,name);
pos = strstr(tmpname,substr);
len = tmpname - pos;

if (len < 0) outname.Resize(TMath::Abs(len));
else outname = tmpname + strspn(tmpname,substr);

delete [] delname;

return outname;
}//RemoveSubString

When I test this function as macro.C I get the following
correct output:
root [0] .L macro.C
root [1] RemoveSubString(“My_Name_Delete”,“Delete”)
(class TString)"My_Name_"
root [2] RemoveSubString(“My_Name_Delete”,“DELETE”)
(class TString)"My_Name_Delete"
root [3]

Now I add the following debugging code to my function:
TString RemoveSubString(const char *name, const char *substr)
{
TString outname = TString(name);
char *tmpname = new char[strlen(name) + 1];
char *delname = tmpname;
Int_t len = 0;
char *pos;

tmpname = strcpy(tmpname,name);
pos = strstr(tmpname,substr);
len = tmpname - pos;

if (len < 0) outname.Resize(TMath::Abs(len));
else outname = tmpname + strspn(tmpname,substr);
cout << "tmpname= " << tmpname << endl;
cout << "pos= " << pos << endl;
cout << "len= " << len << endl;

delete [] delname;

return outname;
}//RemoveSubString

When I test this function as macro.C I get the following
strange and incorrect output:
root [3] .L macro.C
root [4] RemoveSubString(“My_Name_Delete”,“Delete”)
tmpname= My_Name_Delete
pos= Delete
len= -8
(class TString)"My_Name_"
root [5] RemoveSubString(“My_Name_Delete”,“DELETE”)
tmpname= My_Name_Delete
root [6] RemoveSubString(“My_Name_Delete”,“Delete”)
root [7] .q
pos=

Calling RemoveSubString() the first time gives still the
correct answer, but calling it again suppresses all output!

Does anybody know, why I get this strange behavior?
Is there a hidden error in function RemoveSubString()?

My system: root 4.00/03 from 26 March 2004 on MacOS X 10.3.1

Thank you in advance for your help.

Best regards and Happy Eastern
Christian

2

Hi Christian,

Sorry for not checking your code but if you want to replace
a substring in a TString why not use available functionality:

root [0] TString a(“aapmiesaapmies”)
root [1] a.ReplaceAll(“mies”,"")
(class TString)"aapaap"
root [2]

Best regards , Eddy

3

Dear Eddy

Thank you for this simplified version, which I will use.
(Somehow, I missed this solution.)

Nevertheless, I am curious what the reason for this strange
behavior of my solution could be.

Best regards
Christian

4

Hello Christian,

In your code, you do

pos = strstr(tmpname,substr);

and then,

cout << "pos= " << pos << endl;

If substr is not found in tmpname, pos is 0.
Giving (char*) to cout causes strange behavior.

Thank you
Masa Goto

5

Dear Masaharu

Thank you for giving an explanation to one of the problems.
However, the line before:
cout << "tmpname= " << tmpname << endl;
is also not printed, and without the “cout” lines everything works fine.

Maybe, I do not know enough about the inner workings of CINT.

Best regards
Christian

6

Hello Christian,

As far as I tried on my Cygwin, adding if(pos) just before cout << pos
solves the problem. Will you try it?

if(pos) cout << “pos=” << pos << endl;

I don’t know why output from previous line does not show up. It does, at least, on my Cygwin.

Thank you
Masa Goto

7

Dear Masaharu

Thank you for this solution, now everything works fine, even the
output from the previous line shows up.

Best regards
Christian