Python作业问题：如何在输出数值后添加meters/feet单位

问题原因 #

你直接用width + "meters"失败是因为width是数值类型（int/float），Python不允许数值和字符串直接用+拼接，必须先把数值转成字符串，或者用字符串格式化方法。

可行解决方案 #

方案1：用str()转换数值为字符串 #

把数值变量用str()包裹后再拼接，适配所有Python版本：

if metric == 'meters':
    unit = 'METERS'
    print("Here is your calculated Total Volume:")
    print("You entered the width:   ", str(width), unit)
    print("You entered the height:  ", str(height), unit)
    print("You entered the depth:   ", str(depth), unit)
    print("Calculated Total Volume: ", round(total_volume,2), unit + "^3")
    print()
if metric == 'feet':
    unit = 'FEET'
    print("Here is your calculated Total Volume:")
    print("You entered the width:   ", str(width), unit)
    print("You entered the height:  ", str(height), unit)
    print("You entered the depth:   ", str(depth), unit)
    print("Calculated Total Volume: ", round(total_volume,2), unit + "^3")

方案2：使用f-string（推荐，写法更简洁） #

f-string支持直接在字符串中插入变量，自动处理类型转换，Python 3.6及以上可用：

if metric == 'meters':
    unit = 'METERS'
    print("Here is your calculated Total Volume:")
    print(f"You entered the width:   {width} {unit}")
    print(f"You entered the height:  {height} {unit}")
    print(f"You entered the depth:   {depth} {unit}")
    print(f"Calculated Total Volume: {round(total_volume,2)} {unit}^3")
    print()
if metric == 'feet':
    unit = 'FEET'
    print("Here is your calculated Total Volume:")
    print(f"You entered the width:   {width} {unit}")
    print(f"You entered the height:  {height} {unit}")
    print(f"You entered the depth:   {depth} {unit}")
    print(f"Calculated Total Volume: {round(total_volume,2)} {unit}^3")

方案3：优化代码减少重复 #

两个分支逻辑高度一致，可通过三元表达式提取单位变量，避免重复代码：

unit = 'METERS' if metric == 'meters' else 'FEET'
print("Here is your calculated Total Volume:")
print(f"You entered the width:   {width} {unit}")
print(f"You entered the height:  {height} {unit}")
print(f"You entered the depth:   {depth} {unit}")
print(f"Calculated Total Volume: {round(total_volume,2)} {unit}^3")
print()

内容的提问来源于stack exchange，提问作者norma