Understanding Rust Error E0136: Multiple Main Functions
What is Rust Error E0136?
Rust Error E0136 occurs when a program has more than one main function present. In Rust, the main function is the default entry point for a binary, and having multiple instances of this function is disallowed.
Causes of Rust Error E0136
A common cause of this error is accidentally implementing the main function multiple times within the same program. Here's an example of code that triggers this error:
fn main() {
// ...
}
// ...
fn main() { // error!
// ...
}How to resolve Rust Error E0136
To resolve Rust Error E0136, you need to eliminate the duplicate main functions by renaming one of them or removing it if it's not necessary. Ensure that your program has only one main function, serving as its entry point.
Updated code without the error:
fn main() {
// ...
}
// ...
fn alternative() { // renamed to avoid E0136
// ...
}In case you receive this error while using a library that reuses the main function name, consider contacting the library maintainers or adjusting your own naming. Remember that a well-structured Rust program should have a single entry point and a single main function.