Create a two-dimensional array at runtime: Difference between revisions

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@@ Line 1,937: / Line 1,937: @@
 <lang rust>use std::env;
 fn main() {
-    let mut args = env::args();
+    let mut args = env::args().skip(1).flat_map(|num| num.parse());
-    let rows = args.nth(1).unwrap().parse().unwrap();
+    let rows = args.next().expect("Expected number of rows as first argument");
-    let cols = args.nth(2).unwrap().parse().unwrap();
+    let cols = args.next().expect("Expected number of columns as second argument");
     assert!(rows != 0 && cols != 0);
     // Creates a vector of vectors with all elements initialized to 0.
-    let mut v = init_vec(|| init_vec(|| 0, cols), rows);
+    let mut v = init_vec(rows, || init_vec(cols, || 0));
-    v[rows-1][cols-1] = 4;
+    v[0][0] = 1;
-    println!("{}", v[rows-1][cols-1]);
+    println!("{}", v[0][0]);
@@ Line 1,954: / Line 1,954: @@
 // initialized with the values computed by `f`
-fn init_vec<F,T>(f: F, n: usize) -> Vec<T>
+fn init_vec<F,T>(n: usize, f: F) -> Vec<T>
     where F: Fn() -> T
 {
     let mut vec = Vec::with_capacity(n);
-    for i in 0..n {
+    for _ in 0..n {
         vec.push(f());
     }