如何比较字符串中的数值并显示其中的一个数值？

def compare_and_display_number(string):
    temp_number = ""
    max_number = float('-inf')  # 初始化最大数值为负无穷

    for char in string:
        if char.isdigit():
            temp_number += char
        elif temp_number:
            current_number = float(temp_number)
            if current_number > max_number:
                max_number = current_number
            temp_number = ""

    if temp_number:
        current_number = float(temp_number)
        if current_number > max_number:
            max_number = current_number

    print("最大数值为:", max_number)

# 示例调用
compare_and_display_number("abc123def456ghi789")  # 输出：最大数值为: 789