小编Har*_*ari的帖子

我在debian jessie上安装elasticsearch 1.7.3.它使用默认配置文件并正常工作.但是当我调用sudo /usr/share/elasticsearch/bin/plugin它时会返回一个错误:

Exception in thread "main" org.elasticsearch.env.FailedToResolveConfigException: Failed to resolve config path ["/usr/share/elasticsearch/config/elasticsearch.yml"], tried file path ["/usr/share/elasticsearch/config/elasticsearch.yml"], path file ["/usr/share/elasticsearch/config"/"/usr/share/elasticsearch/config/elasticsearch.yml"], and classpath
        at org.elasticsearch.env.Environment.resolveConfig(Environment.java:291)
        at org.elasticsearch.node.internal.InternalSettingsPreparer.prepareSettings(InternalSettingsPreparer.java:95)
        at org.elasticsearch.plugins.PluginManager.main(PluginManager.java:396)

文件/usr/share/elasticsearch/config/elasticsearch.yml存在,我可以用nano打开他.

有/ etc/default/elasticsearch文件:

# Start Elasticsearch automatically
START_DAEMON=true

# Run Elasticsearch as this user ID and group ID
#ES_USER=elasticsearch
#ES_GROUP=elasticsearch

# Heap Size (defaults to 256m min, 1g max)
#ES_HEAP_SIZE=2g

# Heap new generation
#ES_HEAP_NEWSIZE=

# max direct memory
#ES_DIRECT_SIZE=

# Maximum number of open files, …

Postgresql 9.4具有数组函数.其中之一是array_length(anyarray, int).得到两个论点.

第二个论点是什么？在所有例子中它都有价值1.但是没有地方说它是什么.

我已经打印了一些文字println!.现在我需要清除终端并写新文本.如何清除终端中的所有当前文本？

我试过这段代码.但它只清除了当前的行,并且1在输出中很明显.

fn main() {
    println!("1");
    print!("2");
    print!("\r");
}

我有一个成功编译的简单图表：

use std::collections::HashMap;

type Key = usize;
type Weight = usize;

#[derive(Debug)]
pub struct Node<T> {
    key: Key,
    value: T,
}
impl<T> Node<T> {
    fn new(key: Key, value: T) -> Self {
        Node {
            key: key,
            value: value,
        }
    }
}

#[derive(Debug)]
pub struct Graph<T> {
    map: HashMap<Key, HashMap<Key, Weight>>,
    list: HashMap<Key, Node<T>>,
    next_key: Key,
}
impl<T> Graph<T> {
    pub fn new() -> Self {
        Graph {
            map: HashMap::new(),
            list: HashMap::new(),
            next_key: 0,
        }
    }
    pub fn add_node(&mut self, value: …

我不明白 Rust 如何处理字符串。我创建了一个带有两个字符串字段和一个方法的简单结构。此方法连接两个字段和参数中的字符串。我的代码：

fn main() {
    let obj = MyStruct {
        field_1: "first".to_string(),
        field_2: "second".to_string(),
    };

    let data = obj.get_data("myWord");
    println!("{}",data);
}

struct MyStruct {
    field_1: String,
    field_2: String,
}

impl MyStruct {
    fn get_data<'a>(&'a self, word: &'a str) -> &'a str {
        let sx = &self.field_1 + &self.field_2 + word;
        &* sx
    }
}

运行时出现错误：

src\main.rs:18:18: 18:31 error: binary operation `+` cannot be applied to type `&collections::string::String` [E0369]
src\main.rs:18         let sx = &self.field_1 + &self.field_2 + word;
                                ^~~~~~~~~~~~~
src\main.rs:19:10: …

如何获得指向函数的指针u32？

我有一个函数,指向函数的指针:

fn getter_of_functions<T>(pointer: T) {
    // ...
    /* 

    This code don't compile ...
    let fun_ptr: u32 = unsafe {
        mem::transmute::<T, u32>(callback)
    };

    */
}

fn function() {
    println!("hello ...");
}

getter_of_functions(function);

如何获得它(我必须有一个通用的功能)？我经常犯的错误是:

cannot transmute to or from a type that contains unsubstituted type parameters