将所有值相加,忽略减号

def sum_values(expression):
    result = 0
    current_number = 0
    is_negative = False

    for char in expression:
        if char.isdigit():
            current_number = current_number * 10 + int(char)
        elif char == '-':
            is_negative = True
        elif char == '+':
            if not is_negative:
                result += current_number
            else:
                result -= current_number
            current_number = 0
            is_negative = False

    if not is_negative:
        result += current_number
    else:
        result -= current_number

    return result

expression = "1+2-3+4-5+6"
result = sum_values(expression)
print(f"The sum of the values in the expression is: {result}")