Question

使用C ++ 14编译以下代码，但运行它会导致分段错误。这是由lambda函数捕获引起的（用问号标注）？这样做的正确方法是什么？提前谢谢。

import random
import sys

try:
    randSeed = int(input('Enter Random Seed:\n'))
    random.seed(randSeed)
except ValueError:
    sys.exit("Seed is not a number!")

print('Welcome to Monty Hall Analysis')
print("Enter 'exit' to quit")

while True:

    # Total Number of Games
    testNum = input('How many tests should we run?\n')

    valid = False
    while not valid:
        try:
            if testNum == "exit":
                sys.exit("Thank you for using this program.")
            else:
                testNum = int(testNum)
                valid = True
        except ValueError:
            testNum = input('Please enter a number:\n')
    pStay = 0
    pSwitch = 0  # Also need a running count var for switch
    numGame = 0
    for numGame in range(1, testNum + 1):
        doorList = ['C', 'G', 'G']
        random.shuffle(doorList)
        print('Game', numGame)
        print('Doors:', doorList)
        playerDoor = random.randint(0,2)
        montyDoor = random.randint(0,2)
        print('Player Selects Door', playerDoor+1)
        while montyDoor == playerDoor or doorList[montyDoor] == 'C':
            montyDoor = random.randint(0,2)
        print('Monty Selects Door', montyDoor+1)
        if doorList[playerDoor] == 'C':
            var = 0
        else:
            var = 1

        if var == 0:
            #pStay+=1  - - Not sure why you have two increments for pStay.. only need one.
            print('Player should stay to win.')
            pStay += 1
        if var == 1:
            print('Player should switch to win.')
            pSwitch += 1 # Also increment the pSwitch

    # Print out the percentages
    print('\n')    
    print("Percentage of times player should have STAYED: ",(pStay/testNum) * 100, "%")
    print("Percentage of times player should have SWITCHED: ",(pSwitch/testNum) * 100, "%")

Answer 1

发生分段错误是因为std::function构造函数返回时Process::processFunc引用的Foo对象被销毁。要解决此问题，请Process保留std::function对象的副本。

struct Process {
    Process(const std::function<void()>& processFunc) 
        : processFunc(processFunc) {}
    // ...
    std::function<void()> processFunc;
};

Lambda捕获＆＃39;这个＆＃39;保存为std :: function

1 个答案: