/*
============================================================
Convert a decimal-like value to i64 in Rust.
This program demonstrates:
• Conversion using f64::round(), which rounds to the nearest integer.
• Conversion using f64::trunc(), which truncates toward zero.
• Conversion using "as i64", which also truncates.
• A helper function that prints both results for comparison.
Notes:
• Rust does not have a built-in decimal type.
• f64 is used for decimal values.
• round() returns an f64; cast to i64 afterward.
• trunc() removes the fractional part.
============================================================
*/
fn convert_decimal_to_i64(value: f64) -> i64 {
// Rounds to nearest integer, then cast to i64
value.round() as i64
}
fn cast_decimal_to_i64(value: f64) -> i64 {
// Truncates fractional part toward zero
value as i64
}
fn show_conversions(value: f64) {
println!("Input decimal: {:.4}", value);
let rounded = convert_decimal_to_i64(value);
let truncated = cast_decimal_to_i64(value);
println!("Rounded (round): {}", rounded);
println!("Truncated (as i64): {}", truncated);
println!();
}
fn main() {
// Example values to demonstrate behavior
show_conversions(12.7);
show_conversions(12.3);
show_conversions(-5.8);
show_conversions(42.0); // already an integer
}
/*
run:
Input decimal: 12.7000
Rounded (round): 13
Truncated (as i64): 12
Input decimal: 12.3000
Rounded (round): 12
Truncated (as i64): 12
Input decimal: -5.8000
Rounded (round): -6
Truncated (as i64): -5
Input decimal: 42.0000
Rounded (round): 42
Truncated (as i64): 42
*/
