[Frost] arrays of histograms in root

[Brian Morrison]

Hey all,

I'm trying to save myself several thousand lines of code by using an array
of characters as a means to call my histogram names within a loop.  For
example:

char hist_a[28];
hist_a[0] = final_1575_h1_low;
hist_a[1] = final_1575_h2_low;
hist_a[2] = final_1625_h1_low;
.
.
.

for(int i=0;i<=700;i++){
	if(i<50){ // separate into 50 MeV wide W bins
		num1 = 0;
		num2 = 1;
	}
	else if (i>=50 && i<100){
		num1 = 2;
		num2 = 3;
	}
	else if (i>=100 && i<150){
		num1 = 4;
		num2 = 5;
	}
        .
        .
        .
	for(int j=0;j<=100;j++){	// Mass
		for(int q=0;q<=10;q++){	// Cosine Theta
			// First Helicity
			data = hist_a[num1]->GetBinContent(j,q);
			err = hist_a[num1]->GetBinError(j,q);
                        *manipulate data and error*
                        .
                        .
                        .
			hist_a[num1]->SetBinContent(j,q,data);
			hist_a[num1]->SetBinError(j,q,err);
                        .
                        .
                        .
                }
         }
}

and if I can't get this to work I end up having to do the above action
about 28 times for each run period and again for the higher energy runs
making for a lot of tedious code that can easily have errors crop up in
it.  However, root complains that I have a "non class,struct,union object
hist_a[num1] used with . or ->" on the first attempt to call the histogram
by this means.  I've tried casting the called name into a non-array
character variable but that results in the same error.  I haven't had any
luck finding any information on this on either the root site or the web so
I was hoping someone in the group may have some experience with using
arrays to call histograms.  Thanks in advance.

-Brian