ruby - 如何将 BigDecimal 转换为两位小数的字符串？

Question

我想将 BigDecimal 对象转换为保留两位小数的货币值。我不想四舍五入。我该怎么做？

以下方法均无效:

v = BigDecimal("7.1762")
w = BigDecimal("4.2")

v.to_s('2F')            # => "7.17 62"
v.to_s('F')             # => "7.1762"
v.to_s('%0.2F')         # => "0.71762E1"
v.to_s('%0.2f')         # => "0.71762E1"
v.truncate(2).to_s('F') # => "7.17" # This one looks like it worked
w.truncate(2).to_s('F') # => "4.2"  # But it doesn't pad with the trailing zero(es)

Answer 1

结合BigDecimal#truncate怎么样？和 String#% ？ :

"%.2f" % BigDecimal("7.1762").truncate(2)
# => "7.17"
"%.2f" % BigDecimal("4.2").truncate(2)
# => "4.20"