I am trying to create a file as the header and then open it later to append new records, but it seems I am not doing something correctly, does anyone have an idea?
here is the code below:
I have tried it in several ways to no avail.
file = 'Quizdata5.txt'
users = {}
def header():
headers = ("USERID LOGIN-NAME SURNAME NAME AGE "
" YEAR-GROUP SEX USERNAME\n")
with open(file, 'w') as file1:
file1 .write(headers)
file1.close()
def newUser():
global users
global header
global createLogin
global createPassw
global surname
global name
global age
global y_group
global sex
global z1
createLogin = input("Create login name: ")
if createLogin in users: # check if login name exists
print("\nLogin name already exist, please choose a different name!\n")
else:
createPassw = input("Create password: ")
users[createLogin] = createPassw # add login and password
#return (users[createLogin])
surname = input("Pls enter your surname: ")
name = input("Pls enter ur name: ")
age = input("Pls enter your age: ")
y_group = int(input("Please enter your year group: "))
sex =input("Please enter your sex: ")
print("\nUser created!\n")
print("*********************************")
print(" Your Name is\t" + name, "and it starts with: " + name[0] + "\n")
z1 = createPassw[:3] + age
print(" Your Username is:\t ", z1)
if __name__ =='__main__':
header()
while newUser():
with open(file, 'a') as file2:
rows = ("{:8} {:8} {:8} {:8} {:8} {:8}"
" {:8} {:8} \n".format(createLogin, createPassw,
surname, name, age,
y_group, sex, z1))
file2.write(rows.split())
file2.close()
#enter code here
Working version below. Note that I changed your input
statements to raw_input. I'm using Python 2.7. Main things needed:
Seems to be working now and ready for more improvements. Build a little and test until working, then build more - saves a ton of time!
file = 'Quizdata5.txt'
users = {}
def header():
headers = "USERID LOGIN-NAME SURNAME NAME AGE YEAR-GROUP SEX USERNAME\n"
with open(file, 'r') as file1:
firstLine = file1.readline()
print firstLine
if firstLine == headers:
print 'Headers present'
return
with open(file, 'w') as file1:
file1.write(headers)
def newUser():
userList = []
with open(file, 'r') as file1:
Lines = file1.readlines()
for line in Lines[1:]:
lineArray = line.split(' ')
userList.append(lineArray[0])
print userList
global users
global header
global createLogin
global createPassw
global surname
global name
global age
global y_group
global sex
global z1
createLogin = raw_input("Create login name or enter 'exit' to quit: ")
if createLogin == 'exit':
return False
while createLogin in userList: # check if login name exists
print("\nLogin name already exist, please choose a different name!\n")
createLogin = raw_input("Create login name or enter 'exit' to quit: ")
createLogin = createLogin.strip()
if createLogin == 'exit':
print('Goodbye for now.')
return False
createPassw = raw_input("Create password: ")
users[createLogin] = createPassw # add login and password
# return (users[createLogin])
surname = raw_input("Pls enter your surname: ")
name = raw_input("Pls enter ur name: ")
age = raw_input("Pls enter your age: ")
y_group = int(raw_input("Please enter your year group: "))
sex = raw_input("Please enter your sex: ")
print("\nUser created!\n")
print("*********************************")
print(" Your Name is\t" + name, "and it starts with: " + name[0] + "\n")
z1 = createPassw[:3] + age
print(" Your Username is:\t ", z1)
return True
if __name__ =='__main__':
header()
while newUser() == True:
with open(file, 'a') as file2:
row ="{a} {b} {c} {d} {e} {f} {g} {h}\n".format(
a=createLogin, b=createPassw, c=surname, d=name, e=age, f=y_group, g=sex, h=z1)
file2.write(row)
Without just rewriting your code outright, your problem is the line
while newUser():
This means call newUser()
, and execute the indented code only if the return value of newUser()
, evaluated as a boolean, returns True
. That is bool(newUser()) is True
.
Now the questions are
a) What does newUser()
return and, b) What does bool()
mean?
First b: All objects in Python have some "boolean" value associated with it, True
or False
. For a lot of built-in types their boolean evaluation makes sense. For example the integer 0
is treated as False
in a boolean context, while any non-zero integer is treated as True
. This is the case in most any programming language with some exceptions.
Similarly an empty list []
is False
in a boolean context (which is why we can write things like if not my_list: ...
to test if a list is empty) while any non-empty list is treated as True
and so on.
As for a:
Your newUser()
function doesn't explicitly return and any result, because you don't have a return
statement (Tom's solution added some). What you want to do is return a True
-ish value when a new user is added, and a False
-ish value when no new users are to be added. But since you don't return anything, in fact, the default return value for functions if Python, if you don't explicitly return
, is a value called None
and it is always False
.
So the end result is that the code under your while
statement is never run.
If you're ever in doubt about what your code is doing walk through it line by line and see exactly what it's doing--what functions are returning and what values are being assigned to variables--by using the pdb
debugger (Google will direct you quickly to some good tutorials). With Python in particular there's no reason to ever be in the dark about what your code is actually doing.
The technical post webpages of this site follow the CC BY-SA 4.0 protocol. If you need to reprint, please indicate the site URL or the original address.Any question please contact:yoyou2525@163.com.