Python learning exception

Python learning exception

#============================ Common exceptions ============== ==============
# Print (a); # NameError: name 'A' is not defined variable undefined
# If True: # SyntaxError: unexpected EOF while parsing syntax error
# F = open ("123.txt"); # FileNotFoundError: [Errno 2] No such file or directory: '123.txt 'does not have this file # print (10/0 );
# ZeroDivisionError: the division by zero division is 0. # print (int (""));
# ValueError: invalid literal for int () with base 10: 'A' value conversion is invalid

#-*-Config = UTF-8-*-# ================================ Exception Handling (capture runtime exceptions) ================================## Common exceptions # print (a); # NameError: name 'A' is not defined variable undefined # if True: # SyntaxError: unexpected EOF while parsing Syntax Error # f = open ("123.txt"); # FileNotFoundError: [Errno 2] No such file or directory: '123.txt 'does not have this file # print (10/0); # ZeroDivisionError: division by zero division is 0 Error # print (int ("a"); # ValueError: invalid literal for int () With base 10: the 'A' value conversion is invalid #============================= try-another t syntax ========== =========== def tryTest_1 (): try: print (10/0); catch t: # capture all types of exceptions print ("Zero Error"); # Zero Error # tryTest_1 (); def tryTest_2 (): try: print (10/0); counter t ZeroDivisionError as e: # capture the exception print ("Zero Error") of the specified type; # Zero Error # tryTest_2 (); # case-based game import random; def guessNum (): num = random. randint (0,100); # generate a random number while True: try: inputNu M = int (input (); counter t ValueError as e: print ("enter a number from 1 to"); continue; if num> inputNum: print ("input too small"); if num <inputNum: print ("input too large"); if (num = inputNum): print ("OK"); break; # guessNum (); #======================================================= ========= def tryTest_3 (): try: f = open ("2.txt"); cannot t FileNotFoundError as e: print (" file does not exist "); # file does not exist except T ValueError as e: print ("wrong value"); # tryTest_3 () ;#========================== ===== Try-Modify T-else ==================## if the Exception Code is caught, if no exception occurs, run elsedef tryTest_4 (): try: print (1 + 1); # f = open ("2.txt"); alias t FileNotFoundError as e: print ("file does not exist"); # file does not exist. t ValueError as e: print ("wrong value"); else: print ("No Error"); # tryTest_4 (); #================================== try finally ==================## whether or not to check to exception, will Execute finally Code # function: provides a clearing Mechanism for exception handling events to close files or release resources. Def tryTest_5 (): try: f = open ("2.txt"); finally: print (" file close "); f. close (); # tryTest_5 (); #===================================== try-try t-finally ============ = #1. If no exception is caught in the try statement, after the try code is executed, run the finally statement #2. if an exception is caught in the try statement, run the explain T statement first and then run the finally statement def tryTest_6 (): try: f = open ("2.txt"); alias t FileNotFoundError as e: print (" file does not exist "); finally: print (" file close "); f. close (); # tryTest_6 (); #===================================== try-else t-else-finally ====== ========## 1. If the try statement does not catch exceptions, run the try code and then execute the else statement and finally execute the finally statement #2. If the try statement captures an exception, first execute the finally t statement and then execute the finally statement def tryTest_7 (): try: print (10/1); counter t ZeroDivisionError as e: # capture an exception of the specified type print ("Zero Error"); # Zero Error else: print ("else statement"); finally: print ("finally"); # tryTest_7 (); #================================ with statement ========== ================## Replace the try-again t-finall statement with the with statement to make the code more concise def withTEst (): try: with open ("E: \ python \ w_2.txt") as f: print (f. readline (); character t FileNotFoundError as e: print ("file does not exist"); f. close (); # withTEst (); #=================================== raise statements ==================== ==================## raise actively throws an exception # similar to the throw keyword def raiseTest () in java (): raise IOError ("IO exception"); # raiseTest (); #================================== assert statement ====================== ==========================## assert statement: it is used to check whether the expression is true. If the expression is false, an AssertionError error is thrown. # Syntax: assert expression (determining an expression) # assert expression1, expression2 (determining multiple expressions) import random; def assertTest (n): assert n> random. randint (0, 10); print (n); # assertTest (3 ); # If the input n is greater than the number of randomly generated records, print n # If the input n is less than the number of randomly generated records, the AssertionError is thrown.