expressions and statements in Python and for, while loop instance code

expressions and statements in Python and for, while loop exercises

1) expression

       Commonly used expression operators: X + y, x/y, X/y, ×//, and × y logical operations: X or Y, x and Y, not X Member relational operations: X in Y, x not in Y object instance test: X is y, x isn't is y comparison operation: x < y, x > y, x < = y, x >= y, x = = y, x! = y-bit operation: x |        Y, X & y, x ^ y, x << y, x >> y unary operations:-X, +x, ~x: exponentiation: X * * y index and Shard:        X[i], x[i:j], x[i:j:stride] Call: X (...)        Take attribute: X.attribute tuple: (...)        Sequence: [...]        Dictionary: {...} Ternary selection expression: x if y else z anonymous function: Lambda args:expression generator function Send protocol: Yield x Operation priority: (...), [...], {.        ..}        S[i], S[i:j] s.attribute s (...)        +x,-X, ~x x * * y *,/,//,% +,-<<, >> & ^ | <, <=, A;, >=, = =,! = is, isn't in, not in not and or lambda

2) Statement:

    Assignment Statement    call print    : Print object    if/elif/else: Conditional judgment    for/else: sequence Iteration    while/else: normal loop    pass: Placeholder break    :     continue    def    return    yield    Global: namespace    raise: Triggering exception    import: From     : module Property access    class:    try/except/finally: Catch exception    del: Delete reference    assert: Debug Check    with/as: Environment Manager            Assignment statement:                    Implicit assignment: Import, from, Def, class, for, function parameter                    tuple and list decomposition assignment: When the left side of the assignment symbol (=) is a tuple or list, Python pairs the right object and the left target from the left and right by the location. , the number of different when the exception will be triggered, the way can be sliced,                    multi-target Assignment                    enhancement assignment: + =,-=, *=,/=,//=,%=,

3) for Loop practice

    Exercise 1: Separate display of all elements in the specified dictionary d1, similar to the following K1 v1 k2 v2 ... >>> d1 = {' x ': 1, ' Y ':            2, ' Z ': 3, ' m ': 4} >>> for (k,v) in D1.items (): Print k,v y 2                X 1 Z 3 M 4 Exercise 2: Display the list in l1=["Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" in the index of the odd element; >>> L1 = ["Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"] >>> for I in range (1,len (L1), 2): Print L1[i] Mon Wed Fri Exercise 3: Will belong to the list l1=["S                 Un "," mon "," Tue "," Wed "," Thu "," Fri "," sat ", but not part of the list l2=[" Sun "," mon "," Tue "," Thu "," Sat ", all elements defined as a new list L3;             >>> L1 = ["Sun", "mon", "Tue", "Wed", "Thu", "Fri", "Sat"] >>> L2 = ["Sun", "Mon", "Tue", "Thu", "Sat"]                        >>> L3 = [] >>> for i in l1:if I not in L2: L3.append (i) >>> L3 [' Wed ', ' Fri '] Exercise 4: Known list namelist=[' stu1 ', ' stu2 ', ' stu3 ', ' stu4 ', ' stu5 ', ' stu6 ', ' Stu7                 '], delete the list removelist=[' Stu3 ', ' stu7 ', ' stu9 ']; remove each element that belongs to the Removelist list from the NameList (removelist, but not namelist ignore); >>> namelist= [' stu1 ', ' stu2 ', ' stu3 ', ' stu4 ', ' stu5 ', ' stu6 ', ' stu7 '] >>> removelist = [' Stu3                        ', ' stu7 ', ' stu9 '] >>> for i in Namelist:if i in Removelist: Namelist.remove (i) >>> namelist [' stu1 ', ' stu2 ', ' stu4 ', ' stu5 ', ' Stu6 ']

4) While loop exercise

        Exercise 1: Display all elements of the specified list individually; >>> L1 = [1,2,3,4,5] >>> i = 0 >            >> while I < Len (L1) Print L1[i] i + = 1 1 2 3 4 5 >>> l1 = [1,2,3,4,5] >>> while L            1:print l1.pop (0) 1 2 3 4 5 Exercise 2: The sum of all even numbers within 100; >>> i = 0 >&gt                ;> sum = 0 >>> While I < 101:sum + = i i + = 2                    Print sum 2550 >>> for I in Range (0,101,2):                   Sum+=i Print sum 2550 Exercise 3: Display all keys of the specified dictionary one by one, and indicate the total number of keys after the display is finished; >>> D1 = {' X ': 1, ' Y ': all, ' Z ': i1} >>> = D1.keys () >>> while I1:p               Rint i1.pop (0) Else:print len (d1) x y z 3 Exercise 4: Create a list containing all the odd numbers within 100; >>> D1 = [] >>> i = 1            ;>> While I < 101:d1.append (i) i+=2 >>> print D1 [1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27, 29, 31, 33, 35, 37, 39, 41, 43, 45, 47, 49, 51, 53, 55, 57, 59,  ------------------------------------------            [] >>> for I in range (1,101,2) d1.append (i) >>> print D1 [1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27, 29, 31, 33, 35, 37, 39, 41, 43, 45, 47, 49, 51, 53, 55, 57, 59 , 61, 63, 65, 67, 69, 71, 73, 75, 77, 79, 81, 83, 85, 87, 89, 91, 93, 95, 97, 99] Exercise 5: List l1=[0,1,2,3,4,5,6], list l2=["Sun", "Mon", "             Tue "," Wed "," Thu "," Fri "," Sat ", the element in the first list is the key, and the element in the second list generates a dictionary for the value d1; >>> l1 = [0,1,2,3,4,5,6] >>> L2 = ["Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"] >>> D1 = {} &GT;&G                        T;> count = 0 >>> If len (l1) = = Len (L2): While Count < Len (L1): D1[l1[count]] = L2[count] Count + = 1