Question

我正在编写一个简单的程序来创建矩阵并对其执行某些操作。我以前用python 2.7编写了该程序，并且运行良好。但是，它似乎不适用于python 3.7。提示用户输入矩阵的行和列，输入两者的值（浮点数）。但是，只要用户输入“退出”，它就会再次要求用户输入行和列。如果有人能告诉我为什么它不退出while循环“ while value！= quit1：”，那将不胜感激。

There also is a ValueError (cannot convert string to float: 'quit')

无论何时我在程序后键入“ quit”，因为在键入值时该值都会转换为float。我注释掉了value = float（value）行，以测试它是否会退出while循环。取消注释的行将返回ValueError。谢谢

def main():

    print("Welcome to the matrix program!")
    print("Enter the number of dimensions: ")
    m = int(input("Enter number of rows: "))
    n = int(input("Enter number of columns: "))
    matrix = []
    for i in range(m):
        matrix.append([])
        for j in range(n):
            matrix[i].append(0)
    print(matrix)
    value = 0
    quit1 = str("quit").upper
    while value != quit1:
        row_loc = int(input("Enter a row location: "))
        col_loc = int(input("Enter a column location: "))
        value = input("Enter a value for the matrix of QUIT to stop: ")
        if value != quit1:
            value = float(value)
            matrix[row_loc-1][col_loc-1] = value
        else:
            value = quit1

    print(matrix)
    choices = "What would you like to do? \n(1) APPLY \n(2) TRANSPOSE \n(3) PRINT \n(4) QUIT"
    print(choices)
    choice = int(input("Choice: "))

Answer 1

因此，看来您的问题由两部分组成。之所以出现ValueError是因为value = float("QUIT")正在if语句中运行。但是，首先将它放入if语句的原因是quit1在()函数调用中缺少upper，因此您可能应该标准化输入。这样的事情应该起作用：

def main():

    print("Welcome to the matrix program!")
    print("Enter the number of dimensions: ")
    m = int(input("Enter number of rows: "))
    n = int(input("Enter number of columns: "))
    matrix = []
    for i in range(m):
        matrix.append([])
        for j in range(n):
            matrix[i].append(0)
    print(matrix)
    value = 0
    quit1 = str("quit").upper()
    while value != quit1:
        row_loc = int(input("Enter a row location: "))
        col_loc = int(input("Enter a column location: "))
        value = input("Enter a value for the matrix of QUIT to stop: ")
        if value.upper() != quit1:
            value = float(value)
            matrix[row_loc-1][col_loc-1] = value
        else:
            value = quit1

    print(matrix)
    choices = "What would you like to do? \n(1) APPLY \n(2) TRANSPOSE \n(3) PRINT \n(4) QUIT"
    print(choices)
    choice = int(input("Choice: "))

您还可以通过修改while语句中的相同内容并删除else

来进一步简化逻辑

输入矩阵值后无法突破while循环

1 个答案: