取整时，如何舍入、向上舍入、向下舍入？ [课程编码3954]

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取整时，如何舍入、向上舍入、向下舍入？_{vkjwoxaycgwmg}
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有以下三种情况：

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1.舍入 (X)：舍入函数返回舍入到最接近整数的值。它不考虑舍入的方向。

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例：round(3.1) = 3round(3.5) = 4round(-3.7) = -4ncozkpzmvcjzqorakpzyvpg

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2.向上舍入 (x)：向上舍入函数将值返回为大于或等于 x 的最大整数值。_{vkjwoxaycgwmg}
例：roundup(3) = 3roundup(3.1) = 4roundup(-3.7) = -3ptyekragyyqggnom

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3.向下舍入 (x)：向下舍入函数将值返回为小于或等于 x 的最小整数值。bmyswxafxcdziilgu
例：rounddown(3) = 3rounddown(3.7) = 3rounddown(-3.7) = -4

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