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Lines and Indentation in Python
Python provides no braces to indicate blocks of code for class and function definitions or flow control. Blocks of code are denoted by line indentation, which is rigidly enforced.
The number of spaces in the indentation is variable, but all statements within the block must be indented the same amount. For example −
if True: print "True" else: print "False"
However, the following block generates an error −
if True: print "Answer" print "True" else: print "Answer" print "False"
Thus, in Python all the continuous lines indented with same number of spaces would form a block. The following example has various statement blocks −
Note − Do not try to understand the logic at this point of time. Just make sure you understood various blocks even if they are without braces.
#!/usr/bin/python import sys try: # open file stream file = open(file_name, "w") except IOError: print "There was an error writing to", file_name sys.exit() print "Enter '", file_finish, print "' When finished" while file_text != file_finish: file_text = raw_input("Enter text: ") if file_text == file_finish: # close the file file.close break file.write(file_text) file.write("\n") file.close() file_name = raw_input("Enter filename: ") if len(file_name) == 0: print "Next time please enter something" sys.exit() try: file = open(file_name, "r") except IOError: print "There was an error reading file" sys.exit() file_text = file.read() file.close() print file_text
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