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authorDivay Prakash <divayprakash@users.noreply.github.com>2019-12-23 23:14:50 +0530
committerGitHub <noreply@github.com>2019-12-23 23:14:50 +0530
commit16dc074e39f5f996639f23f4d6812c211ae5d22d (patch)
tree63be0d1a3885201f3d13f1dc00266fb719f304a7 /rust.html.markdown
parentffd1fed725668b48ec8c11cbe419bd1e8d136ae3 (diff)
parent1d5f3671ea4bc6d7a70c3026c1ae6857741c50a6 (diff)
Merge branch 'master' into master
Diffstat (limited to 'rust.html.markdown')
-rw-r--r--rust.html.markdown20
1 files changed, 15 insertions, 5 deletions
diff --git a/rust.html.markdown b/rust.html.markdown
index 6b75fa87..92794e69 100644
--- a/rust.html.markdown
+++ b/rust.html.markdown
@@ -41,6 +41,7 @@ Rust not only fast, but also easy and efficient to code in.
// 1. Basics //
///////////////
+#[allow(dead_code)]
// Functions
// `i32` is the type for 32-bit signed integers
fn add2(x: i32, y: i32) -> i32 {
@@ -48,6 +49,9 @@ fn add2(x: i32, y: i32) -> i32 {
x + y
}
+#[allow(unused_variables)]
+#[allow(unused_assignments)]
+#[allow(dead_code)]
// Main function
fn main() {
// Numbers //
@@ -88,10 +92,8 @@ fn main() {
let s: String = "hello world".to_string();
// A string slice – an immutable view into another string
- // This is basically an immutable pair of pointers to a string – it doesn’t
- // actually contain the contents of a string, just a pointer to
- // the begin and a pointer to the end of a string buffer,
- // statically allocated or contained in another object (in this case, `s`)
+ // The string buffer can be statically allocated like in a string literal
+ // or contained in another object (in this case, `s`)
let s_slice: &str = &s;
println!("{} {}", s, s_slice); // hello world hello world
@@ -256,11 +258,16 @@ fn main() {
// `while` loop
while 1 == 1 {
println!("The universe is operating normally.");
+ // break statement gets out of the while loop.
+ // It avoids useless iterations.
+ break
}
// Infinite loop
loop {
println!("Hello!");
+ // break statement gets out of the loop
+ break
}
/////////////////////////////////
@@ -281,7 +288,7 @@ fn main() {
// Reference – an immutable pointer that refers to other data
// When a reference is taken to a value, we say that the value has been ‘borrowed’.
// While a value is borrowed immutably, it cannot be mutated or moved.
- // A borrow lasts until the end of the scope it was created in.
+ // A borrow is active until the last use of the borrowing variable.
let mut var = 4;
var = 3;
let ref_var: &i32 = &var;
@@ -290,6 +297,8 @@ fn main() {
println!("{}", *ref_var);
// var = 5; // this would not compile because `var` is borrowed
// *ref_var = 6; // this would not either, because `ref_var` is an immutable reference
+ ref_var; // no-op, but counts as a use and keeps the borrow active
+ var = 2; // ref_var is no longer used after the line above, so the borrow has ended
// Mutable reference
// While a value is mutably borrowed, it cannot be accessed at all.
@@ -300,6 +309,7 @@ fn main() {
println!("{}", *ref_var2); // 6 , // var2 would not compile.
// ref_var2 is of type &mut i32, so stores a reference to an i32, not the value.
// var2 = 2; // this would not compile because `var2` is borrowed.
+ ref_var2; // no-op, but counts as a use and keeps the borrow active until here
}
```