The following program gives different results when executed from CodeBlocks and from cmd -:
#include <iostream>
#include <string>
#define BOOST_FILESYSTEM_NO_DEPRECATED
#include <boost/filesystem.hpp>
using namespace std;
using namespace boost::filesystem;
int main()
{
// A valid existing folder path on my system.
// This is actually the path containing the program's exe.
path source = "D:\\anmol\\coding\\c++\\boost\\boost1\\bin\\release";
cout << "output = " << equivalent( source, "D:" ) << " !!!\n";
return 0;
}
The output from CodeBlocks after running it from inside the IDE -:
output = 0 !!!
The output from cmd by executing boost1
after changing the current directory to the folder containing the executable ( the source
path mentioned in the code ) -:
output = 1 !!!
According to me, the output given by CodeBlocks should be the correct one.
I am running this program on Windows 7 SP1 64-bit and CodeBlocks 13.12.
I am using TDM-GCC 4.9.2 (32-bit) and Boost 1.57 to build this program.
The wrong output from cmd comes only if I execute the program after changing the current directory to the folder containing the executable.
If I keep the cmd's current directory to some other folder, the correct output is displayed.
EDIT -:
The original problem I was trying to solve was to check whether a file/directory was a descendant of another directory or not.
For accomplishing that, I implemented the following code -:
#include <iostream>
#include <string>
#define BOOST_FILESYSTEM_NO_DEPRECATED
#include <boost/filesystem.hpp>
using namespace std;
using namespace boost::filesystem;
// Returns the difference in height in the filesystem tree, between the directory "parent" and the file/folder "descendant"
static int HeightDiff( const path parent, path descendant )
{
int diff = 0;
while ( !equivalent( descendant, parent ) )
{
descendant = descendant.parent_path();
if ( descendant.empty() )
{
diff = -1; // "descendant" is not a descendant of "parent"
break;
}
diff++;
}
return diff;
}
// Returns true if the file/folder "descendant" is a descendant of the directory "parent"
static bool IsDescendant( const path parent, path descendant )
{
return HeightDiff( parent, descendant ) >= 1;
}
int main( int argc, char** argv )
{
if ( isDescendant( canonical( argv[1] ), canonical( argv[2] ) ) )
{
cerr << "The destination path cannot be a descendant of the source path!! Please provide an alternate destination path !!" << endl;
}
}
Now, if I executed the code with argv[1]="D:\anmol\coding\c++\boost\boost1\bin\release"
and argv[2]="D:\anmol\coding\c++\boost\boost1\bin"
, it would return true
, when it should have returned false
instead. (Since, in this case, the parent
is actually the descendant of descendant
)
The reason for this is that during the while loop in HeightDiff()
, after some iterations, descendant
would take the value D:
. Consequently, equivalent()
will return true and stop the loop one step before descendant
becomes an empty string.
I did not know earlier that D:
refers to the current directory, and hence asked this question.
Is there any way to modify the HeightDiff
function so that it gives the correct output ?
Will replacing the equivalent()
condition with while(descendant != parent)
give correct output on all the cases ?
If not, then is there any other solution ?
After replacing the equivalent
condition with while(descendant != parent)
, the program is working correctly.
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