# replace! {#replace}

**Parent topic:**[Functions](../../Functions/category.md)

## Syntax {#topic_fgt_k1q_ncc}

`replace!(X, oldValue, newValue)`

## Details {#topic_cqf_n1q_ncc}

Please refer to [replace](replace.md). The only difference between `replace` and `replace!` is that the latter assigns the result to *X* and thus changing the value of *X* after the execution.

