Question

我需要从给定的字符串中评估表达式，例如“（19 +（（91 -96）-13））”但我必须自己制作te算法，我不能使用eval（）或其他东西类似。

我已经尝试了很多这个代码，但它给了我带负数的问题：

while counter < 1:
    chunks = []
    counter2 = 1

    for character in operation:
        if character.isdigit():
            if chunks[-1].isdigit():   # If the last chunk is already a number
                chunks[-1] += character  # Add onto that number
            else:
                chunks.append(character) # Start a new number chunk
        elif character in '+-/*()':
            chunks.append(character)  # This doesn't account for `1 ++ 2`.

    for e in reversed(chunks):
        if e == '(':
            counter2 = len(chunks) - counter2
            break
        else:
            counter2 = counter2 + 1

    if chunks[counter2+2] == '+':
        result2 = int (chunks[counter2+1]) + int (chunks[counter2+3])
    elif chunks[counter2+2] == '-':
        result2 = int (chunks[counter2+1]) - int (chunks[counter2+3])
    elif chunks[counter2+2] == '*':
        result2 = int (chunks[counter2+1]) * int (chunks[counter2+3])
    elif chunks[counter2+2] == '/':
        result2 = int (chunks[counter2+1]) / int (chunks[counter2+3])


    chunks[counter2] = ''
    chunks[counter2 + 1] = ''
    chunks[counter2 + 2] = str (result2)
    chunks[counter2 + 3] = ''
    chunks[counter2 + 4] = ''

    operation = ''.join(chunks)

不要注意while条件，我正在更新它，因为我需要检查

Answer 1

您应该尝试更多地自行调试代码。你遇到的问题是int转换正在＆＃34; - ＆＃34;而不是＆＃34; -5＆＃34;。你需要结合＆＃34; - ＆＃34;和序列中的next整数并将其转换为int并使用。 temp = str（chunk [counter2 + 3]）+ str（chunk [counter2 + 4]）

从String - Python评估数学表达式

1 个答案: