初学Python代码问题

Question

5.2编写一个程序，重复提示用户输入整数，直到用户输入“完成”为止。一旦完成＆＃39;输入后，打印出最大和最小的数字。如果用户输入除有效数字以外的任何内容，请使用try / except捕获它并输出相应的消息并忽略该数字。输入问题5.1的书中的数字，然后匹配所需的输出。

这是我的代码：

largest = None
smallest = None
while True:
    inp = raw_input("Enter a number: ")
    if inp == "done" : break
    try:
        num = float(inp)
    except:
        print "Invalid input"
    if smallest is None:
        smallest = num
    elif num < smallest:
        smallest = num
    elif num > largest:
        largest = num

    continue

print "Maximum is", largest
print "Minimum is", smallest

******请让我知道此代码中的逻辑错误*****

Answer 1

答：你永远不会将最大分配为无。

B：如果float（inp）失败，你仍然会尝试继续。你不应该。当你可以将那些if / elif语句移动到try块中时，我建议不要这样做，因为你冒着意外捕获你不应该的东西的风险。相反，请使用try / except忽略else块。

在同一行中，除了您想要的错误而不是所有错误之外，这是一个很好的做法。

C：没有必要继续

largest = None
smallest = None
while True:
    inp = raw_input("Enter a number: ")
    if inp == "done" : break
    try:
        num = float(inp)
    except ValueError: #and not all errors!
        print "Invalid input"
    else: 
        # This block will execute if no exception is caught.
        # Yes, this is valid python.
        if smallest is None: #first number!
            smallest = num
            largest = num
        elif num < smallest:
            smallest = num
        elif num > largest:
            largest = num

print "Maximum is", largest
print "Minimum is", smallest

Answer 2

编写一个程序，反复提示用户输入整数，直到用户输入“完成”。输入“完成”后，打印出最大和最小的数字。如果用户输入除有效数字以外的任何内容，请使用try / except捕获它并输出相应的消息并忽略该数字。

largest = None
smallest = None

while True:
    inp = raw_input("Enter a number: ")

    if inp == "done":
        break

    try:
        num = int(inp)

        if smallest is None:
            smallest = num
        elif num < smallest:
            smallest = num
        elif num > largest:
           largest = num
    except:
        print "Invalid input"

    continue

print "Maximum is", largest
print "Minimum is", smallest 

如果执行后出现不匹配，则出现

错误

Answer 3

largest = None
smallest = None
while True:
    inp = raw_input("Enter a number: ")
    if inp == "done" : break
    try:
        num = int(inp)
    except:
        print "Invalid input"
        continue
    if smallest is None:
        smallest = num
    elif num < smallest:
        smallest = num
    if largest is None:
        largest = num
    elif num > largest:
        largest = num

print "Maximum is", largest
print "Minimum is", smallest

Answer 4

largest = None
smallest = None
while True:
    num = raw_input("Enter a number:")
    if num == "done": break
    try: 
       nom = int(num)
    except: 
       print "Invalid input"
       continue

    if largest is None:
        largest = nom
    elif nom >  largest:
        largest = nom

    if smallest is None:
        smallest = nom
    elif nom < smallest:
        smallest = nom


print "Maximum is", largest
print "Minimum is", smallest

Answer 5

您应该在try：block中包含逻辑以逻辑运行此程序。即使你将逻辑放在catch块中，它也会运行。

在捕获之后放置逻辑（if / else）无法计算在捕获错误之前输入的数字的最高和最低数字。

正确方法

largest = None
smallest = None
while True:
    num = input("Enter a number: ")
    if num == 'done': break
    try:
        ival = int(num)
                # This block will execute if no exception is caught.
        # Yes, this is valid python.
        if smallest is None: #first number!
            smallest = ival
            largest = ival
        elif ival  largest:
            largest = ival

    except ValueError: #and not all errors!
        print ('Invalid input')
        continue 


print('Maximum is', largest)
print('Minimum is', smallest)

错误的方法

    largest = None
    smallest = None
    while True:
        num = input("Enter a number: ")
        if num == 'done': break
        try:
            ival = int(num)
        except ValueError:
            print ('Invalid input')
            continue 
    if smallest is None:
                smallest = ival
                largest = ival
            elif ival  largest:
                largest = ival

    print('Maximum is', largest)
    print('Minimum is', smallest)

Answer 6

代码：

largest = None
smallest = None

while True:
num = input("Enter a number: ")
if num == "done":
    break
try:
    n = int(num)
    if smallest is None or n < smallest:
        smallest = n
    if largest is None or n > largest:
        largest = n
except ValueError:
    # num cannot be converted to an int
    print ("Invalid input")

print("Maximum is", largest)
print("Minimum is", smallest)

输出：

Invalid input
Maximum is 10
Minimum is 2

Answer 7

   largest = 0
smallest = None
while True:
    num = input("Enter a number: ")
    if num == "done" : 
        break
    try:
        num1=int(num)
        if(num1>largest):
            largest=num1
        elif smallest is None or num1<smallest:
             smallest = num1
    except:
        print('Invalid input')
        continue


print("Maximum is", largest)
print("Minimum is",smallest)

Answer 8

largest = None
smallest = None
while True:
    inp = raw_input("Enter a number: ")
    if inp == "done" : break
    try:
        num = int(inp)
    except ValueError: #and not all errors!
        print ("Invalid input")
    else: 
        # This block will execute if no exception is caught.
        # Yes, this is valid python.
        if smallest is None: #first number!
            smallest = num
            largest = num
        elif num < smallest:
            smallest = num
        elif num > largest:
            largest = num

print ("Maximum is", largest)
print ("Minimum is", smallest)

Answer 9

#by Aless
largest  = None
smallest = None
while True:
    num = input("Enter a number: ")
    if num == "done" : break

    try:
        intNum = int(num)
    except ValueError:
        #print('Error: Invalid input', num)
        print('Invalid input')
        continue
    else:
        if (largest  < intNum): largest = intNum
        if (smallest > intNum) or (smallest is None): smallest = intNum

print("Maximum", largest)
print("Minimum", smallest)

Answer 10

largest = 0
smallest = None
while True:
    num = input("Enter a number: ")
    if num == "done" : 
        break
    try:
        num1=int(num)
        if(num1>largest):
            largest=num1
        elif((smallest is None) or(num1<smallest)):
            smallest=num1
    except ValueError:
        print("Invalid input")    
        continue

print("Maximum is", largest)
print("Minimum is",smallest)

Answer 11

largest = None
smallest = None
numbers = []
while True:
    num = input("Enter a number: ")
    if num == "done":
    break
    numbers.append(num)

for value in numbers:
    try:
        value = int(value) 
        if largest is None:
            largest = value
        elif value > largest:
            largest = value
    except:
        continue

for value in numbers:
    try:
        value = int(value)
        if smallest is None:
            smallest = value
        elif value < smallest:
            smallest = value
    except:
        print ("Invalid input")
        continue       `

print("Maximum is", largest)
print("Minimum is", smallest)

Answer 12

largest = None
smallest = None

while True:
inp = input("Enter a number: ")

if inp == "done" : break
try:
    num = float(inp)
except ValueError: 
    print ("Invalid input")
else: 
    if smallest is None:
        smallest = num
        largest = num
    elif num < smallest:
        smallest = num
    elif num > largest:
        largest = num   
print ("Maximum is", int(largest))   
print ("Minimum is", int(smallest))

Answer 13

5.2编写一个程序，反复提示用户输入整数，直到用户输入“ done”为止。输入“完成”后，打印出最大和最小的数字。如果用户输入的数字不是有效数字，请使用try / except进行捕获，然后输入适当的消息并忽略该数字。输入7、2，bob，10和4，然后匹配下面的输出。

largest = None
smallest = None
while True:
    num = input("Enter a number: ")
    if num == "done" :
        break
    try:
        a = int(num)
    except:
        print("Invalid input") 
        continue
    if a > largest:
        largest = a
    if smallest is None:
        smallest = a
    if  a < smallest:
    smallest = a

print("Maximum is", largest)
print("Minimum is", smallest)

输入

7
2
bob
10
4
done

输出

Invalid input
Maximum is 10
Minimum is 2

Answer 14

#试试这个代码。它的工作原理请看截图使用 7,4,bob, 10,4 和最后一个“done”。

largest = None
smallest = None

while True:
    try:
        num = raw_input("Enter a number: ")
        if num == "done":
            break
        if largest is None:
            largest = int(num)
        if int(num) > largest:
            largest = int(num)
        if smallest is None:
            smallest = int(num)
        if int(num) < smallest:
            smallest = int(num)
    except:
        print ("Invalid input")
print ("Maximum is", largest)
print ("Minimum is", smallest)

Answer 15

尝试此代码....

largest = None
smallest = None

while True:
    num = input("Enter a number: ")
    if num == "done" : 
        break 
    try:
        inp=float(num)
    except:
        print("Invalid input")
        continue

for value in [7,2,10,4]: 
    if largest is None:
        largest = value
    elif value>largest:  
        largest=value
        print("Maximum is", largest)            
for value in [7,2,10,4]: 
    if smallest is None:
        smallest = value
    elif value < smallest:
        smallest=value          
        print("Minimum is", smallest)