How to perform ceiling division?

Question

How can I perform ceiling division on an integer? I want to avoid converting to a floating point value.

For example, 7 / 4 should return 2, not 1.

Answer 1

Rust 1.73 Update:

There is u32::div_ceil() on stable now.

While i32::div_ceil() is unstable on nightly.

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Rust stable v1.61.0 branch: ceil(a/b) is (a + b - 1) / b if you know that that addition won't overflow.

Answer 2

From the Rust standard library (minimum version 1.73)

u32: div_ceil

u64: div_ceil

// pub const fn div_ceil(self, rhs: Self) -> Self;
//     Calculates the quotient of self and rhs, 
//     rounding the result towards positive infinity.

let integer: u32 = 122023;
let result = integer.div_ceil(10000); // 13

assert_eq!(7_u32.div_ceil(4), 2);