Re: pass a vector to a void function?
"Default User"
John Brawley wrote:
"Default User"
Please most COMPLETE minimal code that demonstrates the problem. As
shown, you have no headers included, and most of your variables are
undeclared.
NOW I have the problem that the densified example above works
perfectly: the file has content, but the main program's
_apparently_identical_ filewriter and function call, those relevant
pieces extracted and put into my first message, doesn't.
Well, it should give you a starting point.
It did. The problem has got to be inside the function.
At bottom, I post two snippets:
2) an altered version of the *working* one, and
1) a heavily experimented-upon cut-and-paste of the one that doesn't.
You'll notice that the vector is getting into the function, and is usable
there, just not in the way I have to use it...
I'd try to cut down the other program by pieces until it works (or add
parts to the one that does until it breaks.
It makes no sense to me, since the function is essentially independent of
the program (it's a void filewriter only, whose array[] version works fine),
so it should not care about what it gets so long as it gets what it needs
from the function call, and it *is* getting everything it needs:
The nonworking function, notated:
(All else is the same as the working version, same headers, same sort of
call from within main(), etc.)
void it8vout(const vector<double> &pdbv){
ofstream it8vfil;
it8vfil.open ("it8vrawc.3d");
if (it8vfil.is_open()) {
for (long int k=0; k<pNum*5; k+=5) {
double a=pdbv[0+k];
double b=pdbv[1+k];
double c=pdbv[2+k];
cout<<"notice me!"<<c<<"\n"; //Nothing
it8vfil<<a<<" "<<b<<" "<<c<<"\n"; //Nothing
}
cout<<"dis "<<a<<" is "<<b<<" nuts "<<c<<"\n"; //Outputs correct numbers
it8vfil<<"disis"<<pdbv[2]<<"nutsalso\n"; //Outputs to file
//if the above closing brace is here }, Nothing from all four.
}
it8vfil.close();
}
So, how can it be that the function reads the right numbers from vector
pdbv, as is seen by the fact that they can be output from outside of the
critical brace, but inside it where it needs to do tjose things, it doesn't
do them? I'm frazzled by this; it *ought* to work, and what's worse, the
stripped-down model of exactly the same thing, *does* work.
The working version, modified:
#include <vector>
#include <fstream>
#include <ostream>
#include <cstdlib>
#include <iomanip>
using namespace std;
vector<double> vec;
int pNum=5;
void writfil(const vector<double> &vec) {
ofstream it8vfil;
it8vfil.open ("it8test.3d");
if (it8vfil.is_open()) {
for (long int k=0;k<pNum*5;k+=5) {
double a=vec[0+k];
double b=vec[1+k];
double c=vec[2+k];
it8vfil << a << " " << b << " " << c << "\n"; // Works
cout<<a<<" "<<b<<" "<<c<<"\n"; } //check same ##s? =Yes.
}
it8vfil.close();
}
main() {
for (int i=0;i<pNum*5;i++) {
double val=rand()%10000*0.000314159;
vec.push_back(val);
cout<<val<<" ";//check same ##s? Yes.
}
cout<<"\n\n";
writfil(vec);
return 0;
}
.......I can't fathom this.
It cannot be that there's something utterly unrelated --and *unconnected*--
to either the function or its call, that can cause this to screw up inside
the function *right between* correct extraction of numbers from the vector,
and an immediate write-to-file....
....Can it? How?
--
Peace
JB
jb@tetrahedraverse.com
Web: http://tetrahedraverse.com