Very simple argc, argv example that errors

ROOT
1

Let’s say this basic example is in a file named arg_test.C:

[code]#include

using namespace std;

int main(const int argc, const char **argv) {
int a = argc;
cout << "a: " << a << endl;
char*b = argv[0];
cout << "b: " << b << endl;
}[/code]

And it runs with the following commands:

[mwoods] $ root
root [1] .L arg_test.C
root [2] main(23,"test")
a: 23

 *** Break *** segmentation violation
b: 


===========================================================
There was a crash.
This is the entire stack trace of all threads:
===========================================================

Thread 1 (process 15571):
#0  0x00007fff804dac90 in wait4 ()
#1  0x00007fff804ef23e in system ()
#2  0x000000010011e818 in TUnixSystem::StackTrace ()
#3  0x000000010011c19a in TUnixSystem::DispatchSignals ()
#4  <signal handler called>
#5  0x00007fff80460180 in strlen ()
#6  0x0000000100af0e58 in G__G__stream__0_25 ()
#7  0x000000010093cc86 in Cint::G__ExceptionWrapper ()
#8  0x00000001009fbf9c in G__execute_call ()
#9  0x00000001009fc3db in G__call_cppfunc ()
#10 0x00000001009d6413 in G__interpret_func ()
#11 0x00000001009bf263 in G__getfunction ()
#12 0x0000000100a17634 in G__overloadopr ()
#13 0x0000000100a18692 in G__bstore ()
#14 0x00000001009a3587 in G__getexpr ()
#15 0x0000000100a22132 in G__exec_statement ()
#16 0x00000001009d7c35 in G__interpret_func ()
#17 0x00000001009bf263 in G__getfunction ()
#18 0x00000001009933aa in G__getitem ()
#19 0x0000000100997ad7 in G__getexpr ()
#20 0x0000000100a2a41e in G__exec_statement ()
#21 0x000000010097ed86 in G__exec_tempfile_core ()
#22 0x000000010097f096 in G__exec_tempfile_fp ()
#23 0x0000000100a33f54 in G__process_cmd ()
#24 0x000000010002b23e in TCint::ProcessLine ()
#25 0x000000010007b7eb in TApplication::ProcessLine ()
#26 0x00000001012fadbf in TRint::HandleTermInput ()
#27 0x00000001012f9397 in TTermInputHandler::Notify ()
#28 0x00000001012fb2bd in TTermInputHandler::ReadNotify ()
#29 0x000000010011be62 in TUnixSystem::CheckDescriptors ()
#30 0x000000010011c365 in TUnixSystem::DispatchOneEvent ()
#31 0x00000001000b6d7d in TSystem::InnerLoop ()
#32 0x00000001000b89f3 in TSystem::Run ()
#33 0x0000000100079e57 in TApplication::Run ()
#34 0x00000001012f9ffb in TRint::Run ()
#35 0x00000001000019a0 in main ()
===========================================================


The lines below might hint at the cause of the crash.
If they do not help you then please submit a bug report at
http://root.cern.ch/bugs. Please post the ENTIRE stack trace
from above as an attachment in addition to anything else
that might help us fixing this issue.
===========================================================
#5  0x00007fff80460180 in strlen ()
===========================================================


Root > Function main() busy flag cleared

I’m trying to write code I can compile with g++ without ROOT libraries but also have run-able from the ROOT CLI for those so inclined. Why does this standard syntax not work?

2

[quote]Why does this standard syntax not work?[/quote]Humm … maybe because of the syntax error int the call. The main functions is expecting a pointer to a pointer to chars, while the call is ‘main(23,“test”)’ is passing a pointer to chars … (CINT should probably at least warn of the issues).

Anyway, it is usually awkward for the user to try to pass the arguments to the routine using the ‘main’ style and we recommend something like:[code]
#include
using namespace std;

int arg_test(char *message) {
cout << "message: " << messag << endl;
}

#ifndef CINT
int main(const int argc, const char **argv) {
int a = argc;
cout << "a: " << a << endl;
return arg_test(argv[0]);
}
#endif
[/code]and use either compiled as program or on the prompt:root [1] .L arg_test.C root [2] arg_test("test")
Cheers,
Philippe.