if-else inside for loop not working in python

Question

I am writing a simple Python script with if-else condition in a for a loop by reading inputs line by line from a text file. Below is my script. I should get the expected output. Please help! My env.txt contains:

DEV01
DEV02
UAT01
UAT02

Here is the code:

with open("env.txt") as envnames:
 for eachenv in envnames:
 if eachenv=="DEV01" or "DEV02":
 eachenv="dev"
 print (eachenv)
 elif eachenv=="UAT01" or "UAT02":
 eachenv="uat"
 print(eachenv)
 else :
 print('')

Expected:

dev
dev
uat
uat

actual:

dev
dev
dev
dev

• Talha Israr: please add input file
• Lightness Races in Orbit: @TalhaIsrar Unnecessary; problem is clear

Answer 1

The problem is if eachenv=="DEV01" or "DEV02".

you can not check like this. the result will be True if eachenv=="DEV01" otherwise the rusult will be "DEV02", not False. you should go like this:

if eachenv in ["DEV01", "DEV02"]:

also change for eachenv in envnames: to:

for eachenv in envnames.readlines():

• Sivakumar Kayaroganam: This gives me empty output
• Mehrdad Pedramfar: I think all of the solutions here may give you an empty output, because eachenv is not "DEV01" or "DEV01". I think it has an \n at the end. like this: "DEV01\n" @user1557960
• Mehrdad Pedramfar: change it to if eachenv.rstrip() in ["DEV01", "DEV02"] then update me here.
• Mehrdad Pedramfar: Your welcome @user1557960. please consider this: stackoverflow.com/help/someone-answers

Answer 2

 if eachenv=="DEV01" or "DEV02":

Means, if either of the following:

• eachenv is equal to "DEV01"
• "DEV02"

Well, what about "DEV02"? It exists, so that option of the condition is going to be "truthy", so your if will always pass.

This is not how chained conditions work.

You meant:

if eachenv=="DEV01" or eachenv=="DEV02":

Now it's, if either of the following:

• eachenv is equal to "DEV01"
• eachenv is equal to "DEV02"

Yay!

Answer 3

In the line if eachenv=="DEV01" or "DEV02": the second condition is always true:

>>> if "DEV02":
... print('hello')
... 
hello

This happens because the string "DEV02" is an object, therefore will be evaluated True.

@Lightness Races in Orbit gave the right way to write this if statement.