# Label number for a domain with hole

**URL:** https://community.freefem.org/t/label-number-for-a-domain-with-hole/654
**Category:** General Discussion
**Created:** [November 14, 2020, 7:03pm UTC](https://community.freefem.org/t/label-number-for-a-domain-with-hole/654 "2020-11-14T19:03:24Z")
**Posts on this page:** 1
**Page:** 1

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### Author: ![mordechaiy](https://avatars.discourse-cdn.com/v4/letter/m/cc9497/32.png) [@mordechaiy](https://community.freefem.org/u/mordechaiy)
#### Post date: [November 14, 2020, 7:03pm UTC](https://community.freefem.org/t/label-number-for-a-domain-with-hole/654/1 "2020-11-14T19:03:25Z")

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hi to everyone,  
I would like to ask please;

I created a square with a hole using the commands “square” and then “trunc”.

I wrote the following code in FF++ for the square domain with a hole :

//parameters  
real x0=-7.,y0=-7.;//left bottom node of the omega square  
real xF=7.,yF=7.;//right top node of the omega square  
int n=7;  
int N =2^n;//number of partition in each direction  
real xT=-2.1,yT=-2.1;//left bottom node of TRAC square  
real xTF=2.1,yTF=2.1;//right top node of TRAC square

// domain of the problem

int[int] outer=[1,1,1,1], bTRAC=[2,2,2,2];

mesh Th = square(N,N,[x0+(xF-x0)\*x ,y0+(yF-y0)\*y],label=outer, region=1);

mesh ThTRAC = square(N,N,[xT+(xTF-xT)\*x,yT+(yTF-yT)\*y],label=bTRAC,region=2);

mesh Thwithole=trunc(Th,((x\<xT | x\>xTF|y\<yT) | (x\<xT | x\>xTF| y\>yTF)));

I know that if add the following lines:

int outerboundary=1;  
mesh Thwithole=trunc(Th,((x\<xT | x\>xTF|y\<yT) | (x\<xT | x\>xTF| y\>yTF)),label=outerboundary);

Then FF++ would assign the same label for each of the boundaries.  
But, I would like to assign different labels for each of the boundaries, i.e., for the inner boundary and for the outer boundary.

Thanks in advance,  
Mordechai.