Term
| How are files used in various programs/software? |
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Definition
- to retain data
- receive input (read data)
- store output (write data) |
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Term
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Definition
Text: simply contain text in ASCII or Unicode and can be opened by programs like notepad
Binary: not text-based and designed to only be opened by a program that can use data in that format (images, audio files etc) |
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Term
| List and describe the common modes that can be specified when opening/creating files. |
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Definition
Read ('r') - allows reading only (file must exist)
write ('w') - allows writing only (creates or overwrites file)
append ('a') - writes to the end of the file
read/write ('rw') - allows reading and writing |
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Term
| 3 languages for write mode |
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Definition
f = open ('example.text', 'w') - python
$f = fopen ('example.text', 'w') = PHP
f = file.open ('example.text', 'w') = Ruby |
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Term
| Why is it important to close a file |
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Definition
| Once you have finished processing the file, closing it severs its connections w the program and releases the resources |
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Term
| Describe the different ways that you can read data from a file. |
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Definition
- read the entire file at once - gives you a variable containing the whole file.
- use read() method to specify how many bytes or characters to read.
readline() gives the whole line (work through bit by bit)
read() always returns a string - may need to convert to int or float depending on the data |
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Term
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Definition
| an error or condition that occurs while a program is running, causing it to crash or end. Different to syntax error which occur when the code is not valid and wont run at all |
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Term
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Definition
| another control structure that anticipates the potential errors and handles them by redirecting the program |
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Term
| Exception handler that terminates the program |
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Definition
try:
num = (input('Type a number:'))
except ValueError:
print ('Invalid input')
break
print ('You typed:', num) |
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Term
| Exception handler that continues the program |
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Definition
try:
num = (input('Type a number:'))
except ValueError: #default 7
num = 7
print ('You typed:' num) |
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Term
NameError
TypeError
ValueError
IndexError |
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Definition
- raised when you refer to a variable or function that doesn't exist (typo)
- raised when you use wrong data type eg round('string')
- use right data type but the value is not appropriate (outside set range or minus number for age)
- raised when you refer to an index that doesn't exist (eg index[5] in a list of 3 items |
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Term
Else in exception handling
Finally in exceoption handling |
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Definition
Else - run if no exceptions occur
Finally - will always run either after the try block if no exceptions or after the exception handler if they do |
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