# Function memory_grow

1.33.0 · Source

    pub fn memory_grow(const MEM: u32, delta: usize) -> usize

Available on WebAssembly and `target_family="wasm"` only.
Expand description

Corresponding intrinsic to wasm’s `memory.grow` instruction

This function, when called, will attempt to grow the default linear memory by the specified `delta` of pages. The current WebAssembly page size is 65536 bytes (64 KB). If memory is successfully grown then the previous size of memory, in pages, is returned. If memory cannot be grown then `usize::MAX` is returned.

The argument `MEM` is the numerical index of which memory to return the size of. Note that currently the WebAssembly specification only supports one memory, so it is required that zero is passed in. The argument is present to be forward-compatible with future WebAssembly revisions. If a nonzero argument is passed to this function it will currently unconditionally abort.