# Method_#1 by slicing
names = ['A12.txt', 'B34.txt', 'C45.txt']
# discard '.txt'
names = [ filename[:-4] for filename in names]
print( names )
# -----------------------------------------
# Method_#2 by token splitting
names = ['A12.txt', 'B34.txt', 'C45.txt']
# split by '.', and choose the first token
names = [ filename.split('.')[0] for filename in names]
print( names )