报错ValueError: invalid literal for int() with base 10: 'C'，求定位字符串转整数位置

运行代码时触发错误：ValueError: invalid literal for int() with base 10: 'C'，以下是问题分析与修复方案：

原代码 #

def baseball_game (ops):
  record = []
  for i in range (len(ops)):
    if ops[i] == 'C': 
      record.pop()   #I remove last element. I am mot converting into integer.
      print(record)
    if ops[i] == 'D':
      record.append(record[-1] * 2)  #I am doubling the value of last element, which is already an integer.
      print(record)
    if ops[i] == '+':
      record.append(record[-1] + record[-2]) #I am adding last 2 elements, which are NOT integers.
      print(record)
    else:
      record.append(int(ops[i])) #I am converting into integer any value which is NOT 'C', 'D' nor '+'
      print(record)
  return sum(record)

问题定位 #

你当前使用了三个独立的if语句而非elif。当ops[i]为'C'时，第一个if分支执行record.pop()后，后续两个if分支条件不成立，程序会进入else分支，执行int('C')的转换操作——这就是报错的根源。

简单说：'C'虽然被第一个if处理了，但还是会走到else里去转整数，导致报错。

修复方案 #

把后续的if替换为elif，确保每个循环周期只有一个分支执行，同时可以优化循环方式，直接遍历元素而非通过索引访问：

def baseball_game(ops):
    record = []
    for op in ops:
        if op == 'C':
            record.pop()
            print(record)
        elif op == 'D':
            record.append(record[-1] * 2)
            print(record)
        elif op == '+':
            record.append(record[-1] + record[-2])
            print(record)
        else:
            record.append(int(op))
            print(record)
    return sum(record)

内容的提问来源于stack exchange，提问作者Aizzaac