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I've installed z3-solver package from PyPi in my Python3 environment using Anaconda Prompt ( pip install z3-solver ) and that's it.
The package appears in the site-packages/ directory ( the package has _init__.py and all essential files including z3.py ). However, when I tried running this example from Jupyter Notebook, it returns the following message: NameError: name 'Int' is not defined.
I've only used Anaconda for a short time so I'm not sure how installation works. It's really odd because the 'pip install' command works fine most of the times. Did I do something wrong or this package requires more configuration ?

AMC
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CPS_001
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  • Change Int to int – uttejh Apr 12 '20 at 12:40
  • It doesn't work. Int is a class defined in z3 and the example I used is taken from their official Github repo so it's not realated to the syntax. – CPS_001 Apr 12 '20 at 13:01
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    Do you have a file named `z3.py` in your project directory? – sepp2k Apr 12 '20 at 15:15
  • Did you follow the recommendations for using pip with Conda? See, for example: https://www.anaconda.com/using-pip-in-a-conda-environment/. – AMC Apr 16 '20 at 02:30

5 Answers5

4

you have to write:

from z3 import *

which solved my NameError: name 'Solver' is not defined Exception

prerequisites:

pip install z3
pip install z3-solver

code example

from z3 import *
 
def main(): 
    
    s = Solver()
    x = Int('x')
    y = Int('y')
    s.add(x < 10)
florian.isopp
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  • Installing the "z3" package is a mistake. "z3" is an old package for doing a compressed backup to or from AWS servers, unrelated to "z3-solver". – Charles Merriam Sep 03 '23 at 04:14
1

You can run conda install pip and then run the pip install z3-solver.

João Costeira
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1

Sorry for the late update.

I've managed to solve the problem based on this guide.

To permanently change the sys.path variable in Anaconda, I created a .PTH file which contains the path to z3 and put it in site-packages directory.

You might need to copy the libz3.dll file to the right directory in order for it to work. Running pip install z3-solver does download the required files and put them in site-packages but I can't import z3 from anywhere.

Maybe you also need to fix the path after using pip so Anaconda can recognize it. I did everything manually so I'm not sure why pip doesn't work in this case.

That's all I did to install z3 on my Windows. Hope it helps !

Houda
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CPS_001
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0

Had the same problem in 2022.

IMPORTANT:
Install using the following command

pip install z3 z3-solver

I did not know about the z3-solver package so I installed it later but it didn't work. Same issue as you. Could import but the import only included half a dozen special dunder functions like __file__ and others.

After all permutes of install, uninstall, add-to-$PATH ... later I just did this and it worked at once.

PrisionMike
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0

Lots of answers, but I had this problem and found:

  • First, pip install z3 installs an obsolete and unrelated package related to AWS backups.
  • Second, pip install z3-solver installs only the interface to an installed installation of the z3 system, under the python library name z3. It does not install the underlying z3 system and it does warn you that it does not exist. If there is no underlying system, "import * from z3" will execute, but not import any useful functions.
  • Third, the easiest way to install z3 is use your favorite package manager. On macOS, I used brew install z3.

When the installation of both parts works, a good quick test is import * from z3; a,b = Reals('a b'). If these statements execute, you are good.

Charles Merriam
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