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<p>如果输入的字符串不是浮点数,如何显示错误消息“请输入有效数字”?因为当我输入一个字符串时,我会得到一个错误:</p>
<blockquote>
<p>ValueError: could not convert string to float:</p>
</blockquote>
<p>我的代码:</p>
<pre><code> if unknown == 'S':
if units in ('si', 'Si'):
u = float(input("Enter the initial velocity in m/s :"))
v = float(input("Enter the acceleration in m/s : "))
t = float(input("Enter seconds : "))
else:
u = float(input("Enter the initial velocity in yards/s :"))
v = float(input("Enter the acceleration in yards/s : "))
t = float(input("Enter the time take in s : "))
S = 0.5 * (u + v) * t
print("S is " , S)
</code></pre>