请考虑以下代码:
std::map <string,string> myMap;
myMap.insert(std::make_pair("first_key" , "no_value" ));
myMap.insert(std::make_pair("first_key" , "first_value" ));
myMap.insert(std::make_pair("second_key" , "second_value" ));
typedef map<string, string>::const_iterator MapIterator;
for (MapIterator iter = myMap.begin(); iter != myMap.end(); iter++)
{
cout << "Key: " << iter->first << endl << "Values:" << iter->second << endl;
}
输出是:
Key: first_key
Values:no_value
Key: second_key
Values:second_value
意思是第二个任务:
myMap.insert(std::make_pair("first_key" , "first_value" ));
没有发生.
我怎样才能成对,只有当密钥尚未列出时,如果列出了 - 更改其值？
是否有std :: map的通用方法？
在SML中,我必须使用该else部分,因为这些是语言的规则.
else那时我怎么能做什么呢？
fun calc(input : string ) : int =
let
val outStr = ref "someString"
val outInt = ref 0
in
outInt := (validateHelper(input) handle _ => ~1);
if (outInt <> ~1)
then
( outStr := replaceRomanDec(input); (* replace roman number with decimal *)
outInt := (calcMyRomanExpression(!outStr) handle _ => ~1);
)
else (* nada *)
!outInt
end;
我想将两个列表相乘,我在左侧列表中将其乘以右侧列表中的每个元素.
例如:
?- multLists([3,4,2], [4,7,8], R).
R = [[12,16,8],[21,28,14],[24,32,16]].
为此,我编写了一个辅助谓词,它接受一个列表并将其乘以一个标量:
multListElem([], _, _).
multListElem([H|T], Result, Elem) :-
multListElem(T, W, Elem),
Z is H*Elem,
Result = [Z|W].
但现在,当我跑步时,?- multListElem([1,2,3], X, 3).
我得到:
1 ?- multListElem([1,2,3], X, 3).
X = [3, 6, 9|_G1840].
那怪异的尾巴是_G1840什么？
给定代码
function [nImg,mask] = myFunc(img,rl,rh)
[n m] = size(img);
mask = ones(n, m);
% do some stuff
% more
% and more
%
fourierImg = fft2(img); % take the fourier transform 2d for the given image
fourierImg = fftshift(fourierImg); % shift the fourier transform
output = mask.*fourierImg; % calc with the mask % THAT LINE CAUSES
% Warning: Displaying real part of complex input ?
ishifting = ifftshift(output); % grab the DC element
nImg = ifft2(ishifting); % inverse back to …我想在C#with MySql中删除表,只有它存在.
请考虑以下代码:
namespace CSharpMySqlSample
{
class Example2
{
static void Main()
{
String str = @"server=localhost; database=sakila; uid=root; password=root;";
MySqlConnection con = null;
try
{
con = new MySqlConnection(str);
con.Open(); //open the connection
String cmdText = @"drop table `sakila`.`testable` if exists"; // this one drops a table
MySqlCommand cmd = new MySqlCommand(cmdText, con);
cmd.Prepare();
cmd.ExecuteNonQuery(); //execute the mysql command
}
catch (MySqlException err)
{
String outp = err.ToString();
Console.WriteLine("Error: " + err.ToString());
}
finally
{
if (con != null) …考虑一下aspx:
CS.aspx:
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="CS.aspx.cs" Inherits="CS" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
<style type="text/css">
body
{
font-family: Arial;
font-size: 10pt;
}
input
{
width: 200px;
}
table
{
border: 1px solid #ccc;
}
table th
{
background-color: #F7F7F7;
color: #333;
font-weight: bold;
}
table th, table td
{
padding: 5px;
border-color: #ccc;
}
</style>
</head>
<body>
<form id="form1" runat="server">
<table border="0" cellpadding="0" cellspacing="0">
<tr>
<th colspan="3">
Registration
</th>
</tr>
<tr> …考虑一下:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
namespace Multithreading
{
class Program
{
static int result = 0;
static void changeResult1()
{
result = 1;
}
static void changeResult2()
{
result = 2;
}
static void changeResult3()
{
result = 3;
}
static void Main(string[] args)
{
Thread t1 = new Thread(new ThreadStart(changeResult1));
Thread t2 = new Thread(new ThreadStart(changeResult2));
Thread t3 = new Thread(new ThreadStart(changeResult3));
t1.Start();
t2.Start();
t3.Start();
Console.WriteLine(result);
}
}
}
我很确定这段代码是不同步的,这意味着result …
考虑初始化：
function initMyTinymce() {
tinymce.init({
selector: $(this).attr("id"),
directionality: "ltr",
});
}
之后是否可以向tinyMCE添加属性init()？
例如：
plugins: "link,code,textcolor",
relative_urls: false,
convert_urls: false,
remove_script_host: false
我正在使用TinyMce 4.1.6（2014-10-08）。
考虑代码：
const fs = require('fs');
const express = require('express');
const app = express();
const bodyParser = require('body-parser')
// use middleware
app.use(express.json());
app.use(bodyParser.json());
const fileLocation = `${__dirname}/dev-data/data/tours-simple.json`;
const theTours = JSON.parse(fs.readFileSync(fileLocation));
app.patch('api/v1/tours/:id', (req, res) =>{
if (req.params.id * 1 > theTours.length) {
return res.status(404).json({
status: 'fail',
message: 'Invalid ID'
});
}
res.status(200).json({
status: 'success',
data: {
tour: '<Updated tour here ...>'
}
});
});
const port = 3000;
app.listen(port, () => {
console.log(`App is running on port ${port}`);
});
当我尝试从 Postman …
鉴于这一小段代码
//============================================================================
// Name : prwe.cpp
// Author :
// Version :
// Copyright : Your copyright notice
// Description : Hello World in C++, Ansi-style
//============================================================================
#include <iostream>
using namespace std;
int main() {
cout << "Hello World" << endl; // prints Hello World
return 0;
}
此代码在Eclipse下编译,但Console窗口中没有显示任何内容.
知道我做错了什么吗？
谢谢