1.做题须知
这一题告诉我们可以尝试修改下面的输出,在觉得OK之后删除// I AM NOT DONE注释即可进入下一题
// intro1.rs
// About this `I AM NOT DONE` thing:
// We sometimes encourage you to keep trying things on a given exercise, even
// after you already figured it out. If you got everything working and feel
// ready for the next exercise, remove the `I AM NOT DONE` comment below.
// Execute `rustlings hint intro1` or use the `hint` watch subcommand for a hint.
//
// If you're running this using `rustlings watch`: The exercise file will be reloaded
// when you change one of the lines below! Try adding a `println!` line, or try changing
// what it outputs in your terminal. Try removing a semicolon and see what happens!
// I AM NOT DONE
fn main() {
println!("Hello and");
println!(r#" welcome to... "#);
println!(r#" _ _ _ "#);
println!(r#" _ __ _ _ ___| |_| (_)_ __ __ _ ___ "#);
println!(r#" | '__| | | / __| __| | | '_ / _` / __| "#);
println!(r#" | | | |_| __ |_| | | | | | (_| __ "#);
println!(r#" |_| __,_|___/__|_|_|_| |_|__, |___/ "#);
println!(r#" |___/ "#);
println!();
println!服务器托管网("This exercise compiles successfully. The remaining exercises contain a compiler");
println!("or logic error. The central concept behind Rustlings is to fix these errors and");
println!("solve the exercises. Good luck!");
println!();
println!("The source for this exercise is in `exercises/intro/intro1.rs`. Have a look!");
println!("Going forward, the source of the exercises will always be in the success/failure output.");
}
2.基本输出
我们使用{:?}通配输出一下就好了
// intro2.rs
// Make the code print a greeting to the world.
// Execute `rustlings hint intro2` or use the `hint` watch subcommand for a hint.
fn main() {
println!("Hello {:?}!","world");
}
3.变量绑定
由于Rust里面的变量完全属于主人,所以我们需要使用let语句来对变量进行绑定
// variables1.rs
// Make me compile!
// Execute `rustlings hint variables1` or use the `hint` watch subcommand for a hint.
fn main() {
let x = 5;
println!("x has the value {}", x);
}
4.变量类型
这一题告诉我们变量需要类型,给类型只需要我们对其赋值即可,rust会自动分配他的类型
// variables2.rs
// Execute `rustlings hint variables2` or use the `hint` watch subcommand for a hint.
fn main() {
let x=3;
if x == 10 {
println!("x is ten!");
} else {
println!("x is not ten!");
}
}
5.指定变量类型
我们需要对变量初始化赋值才能使用,而且可以使用:i32指定变量为32位整数
// variables3.rs
// Execute `rustlings hint variables3` or use the `hint` watch subcommand for a hint.
fn main() {
let x: i32=3;
println!("Number {}", x);
}
6.创建可变类型变量
不设置变量为可变类型,就会在改变时报错
// variables4.rs
// Execute `rustlings 服务器托管网hint variables4` or use the `hint` watch subcommand for a hint.
fn main() {
let mut x = 3;
println!("Number {}", x);
x = 5; // don't change this line
println!("Number {}", x);
}
7.重新绑定(变量遮蔽)
当需要用一个变量读取不同类型的数据的时候 可以使用let+数据类型重新创建一个
// variables5.rs
// Execute `rustlings hint variables5` or use the `hint` watch subcommand for a hint.
fn main() {
let mut number = "T-H-R-E-E"; // don't change this line
println!("Spell a Number : {}", number);
let number:i32= 3; // don't rename this variable
println!("Number plus two is : {:?}", number );
}
8.常量申明
常量不仅仅默认不可变，而且自始至终不可变，因为常量在编译完成后，已经确定它的值。
常量使用 const 关键字而不是 let 关键字来声明，并且值的类型必须标注
// variables6.rs
// Execute `rustlings hint variables6` or use the `hint` watch subcommand for a hint.
const NUMBER:i32 = 3;
fn main() {
println!("Number {}", NUMBER);
}
9.书写函数
使用fn funName(){}来创建一个函数申明,然后在main函数里面调用
// functions1.rs
// Execute `rustlings hint functions1` or use the `hint` watch subcommand for a hint.
fn call_me(){
println!("Hello Rust");
}
fn main() {
call_me();
}
10.函数传入形参需要指定类型
形参需要申明传入的变量的类型
// functions2.rs
// Execute `rustlings hint functions2` or use the `hint` watch subcommand for a hint.
fn main() {
call_me(3);
}
fn call_me(num:i32) {
for i in 0..num {
println!("Ring! Call number {}", i + 1);
}
}
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