前中后缀表达式转换代码

下面是将中缀表达式转换为前缀表达式的代码：

def infix_to_prefix(expression):
    # 定义运算符的优先级
    precedence = {'+': 1, '-': 1, '*': 2, '/': 2, '^': 3}
    stack = []
    prefix = []
    for char in reversed(expression):
        if char.isalnum():
            prefix.append(char)
        elif char == ')':
            stack.append(char)
        elif char == '(':
            while stack and stack[-1 != ')':
                prefix.append(stack.pop())
            stack.pop()
        else:
            while stack and precedence[char < precedence.get(stack[-1], 0):
                prefix.append(stack.pop())
            stack.append(char)
    while stack:
        prefix.append(stack.pop())
    return ''.join(reversed(prefix))

expression = "(A*(B-C/D))*E"
prefix_expression = infix_to_prefix(expression)
print("前缀表达式:", prefix_expression)

下面是将中缀表达式转换为后缀表达式的代码：

def infix_to_postfix(expression):
    # 定义运算符的优先级
    precedence = {'+': 1, '-': 1, '*': 2, '/': 2, '^': 3}
    stack = []
    postfix = []
    for char in expression:
        if char.isalnum():
            postfix.append(char)
        elif char == '(':
            stack.append(char)
        elif char == ')':
            while stack and stack[-1 != '(':
                postfix.append(stack.pop())
            stack.pop()
        else:
            while stack and precedence[char <= precedence.get(stack[-1], 0):
                postfix.append(stack.pop())
            stack.append(char)
    while stack:
        postfix.append(stack.pop())
    return ''.join(postfix)

expression = "(A*(B-C/D))*E"
postfix_expression = infix_to_postfix(expression)
print("后缀表达式:", postfix_expression)

希望以上代码能够帮到你！<span class="em">1</span><span class="em">2</span><span class="em">3</span>
#### 引用[.reference_title]
- *1* [中缀表达式，前缀表达式，后缀表达式之间的相互转换和代码表示](https://blog.csdn.net/FYSGXFZ/article/details/100620836)[target="_blank" data-report-click={"spm":"1018.2226.3001.9630","extra":{"utm_source":"vip_chatgpt_common_search_pc_result","utm_medium":"distribute.pc_search_result.none-task-cask-2~all~insert_cask~default-1-null.142^v92^chatsearchT0_1"}}] [.reference_item style="max-width: 50%"]
- *2* *3* [前缀、中缀和后缀表达式详解，中缀表达式到后缀表达式的转换规则，以及后缀表达式的计算规则，附计算代码](https://blog.csdn.net/yldmkx/article/details/109537911)[target="_blank" data-report-click={"spm":"1018.2226.3001.9630","extra":{"utm_source":"vip_chatgpt_common_search_pc_result","utm_medium":"distribute.pc_search_result.none-task-cask-2~all~insert_cask~default-1-null.142^v92^chatsearchT0_1"}}] [.reference_item style="max-width: 50%"]
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