We test three ways of writing data to existing files in order to discover some basic rules of data storage.
# file_append_1.py
#>>>>>>>>>>>>>>>>>
# Open an existing file and add (append) data to it.
filename_1 = "/constr/test_write_1.dat"
filly = open(filename_1,"a") # Open a file in append mode
filly.write("
")
filly.write("This is number four and he has reached the door")
for i in range(0,5):
filename_2 = "/constr/test_write_2.dat"
filly = open(filename_2,"a") # Create a file in append mode
filly.write("This is number five and the cat is still alive")
filename_3 = "/constr/test_write_2.dat"
filly = open(filename_3,"w") # Open an existing file in # write mode
# The command below WILL fail "w" is really "overwrite"
filly.write("This is number six and they cannot find the fix")
What make up the first method are two things: firstly, we open the file for appending ("a") which means we will add data to what is already in the file. Nothing will be destroyed or overwritten. Secondly, we separate the new data from the old with the line
filly.write("
")
The second method works, but is a very bad practice because there is no way of separating different entries.
The third method wipes out whatever was previously stored in the file.
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