Category Archives: How to Fix

Solution: about the problem “C + + – unresolved inclusion: < iostream >“

Problem description

Develop C + + program with eclipse for C + + and CDT plug-in and compilation tool MinGW, write in the head of C + + source program

#include <iostream>
#include <stdio>

When you wait for such a standard library, the editor will prompt:

Unresolved inclusion: <iostream>

resolvent

First, select the project name, in the selection menu: Project & gt; properties & gt; C / C + + general & gt; preprocessor includes ≫ providers
and check “CDT GCC build in compiler settings”, then click the Apply button.

I’ve tried other solutions on the Internet, but they don’t work.

Access restriction: the type ‘application’ is not API (restriction on required LIB)

When using eclipse to build JavaFX with jdk8 for the first time, a compiler error occurred

Access restriction: The type ‘Application’ is not API (restriction on required library ‘E:\JAVA\jdk1.8\jre\lib\ext\ jfxrt.jar ‘)

 

Solution: right click the project name — & gt; build path — & gt; configure build path — & gt; select JRE System Library — & gt; remove — & gt; add library to add system JRE library

 

Android Studio could not resolve resource

Refer here: http://blog.csdn.net/dong19870625/article/details/50833433

Original text:

In the development project, the XML file suddenly appears
couldn’t resolve resource @ color / title_ The color (58 similar errors not show) problem caught people off guard. It’s no problem to write the color and other resource files directly, but it’s not the fundamental solution to the problem

Android Studio just gets crazy. But a restart ain’t always enough.

Invalidate your caches and restart.

File -> Invalidate Caches / Restart… -> Invalidate and Restart

According to the above practice, the effect is good, solved my problem, the original as itself also has cache

reference resources: http://stackoverflow.com/questions/8390733/relativelayout-couldnt-resolve-resource-android

———————————————

I also met similar, but I can’t find the relevant style. It can’t be displayed normally in the preview, but it runs normally. No matter refresh or rebuild, it can’t be eliminated. Just follow the above procedure

The use of BibTex

BibTex is used as the reference format management library of latex documents.

The operation steps are as follows:

Step 1: create a BibTex file;

Create a new TXT file and change the suffix to bib, that is, create a BibTex reference library. For example, the name of the created BibTex library is: ref.bib .

Step 2: add the content of the quoted article;
0

Copy the BibTex format content of the document to be quoted to ref.bib The BibTex content of a document to be cited is as follows:
the BibTex content of a document to be cited is as follows:

@Inbook{Wille1982,
author="Wille, Rudolf",
editor="Rival, Ivan",
title="Restructuring Lattice Theory: An Approach Based on Hierarchies of Concepts",
bookTitle="Ordered Sets: Proceedings of the NATO Advanced Study Institute held at Banff, Canada, August 28 to September 12, 1981",
year="1982",
publisher="Springer Netherlands",
address="Dordrecht",
pages="445--470",
isbn="978-94-009-7798-3",
doi="10.1007/978-94-009-7798-3_15",
url="http://dx.doi.org/10.1007/978-94-009-7798-3_15"
}

Step 3: add cite package to latex document;

Add package reference to latex document: usepackage {cite}.

Step 4: add reference configuration;
Step 4: add reference configuration

Add the BibTex library reference in latex document. Where you want to display the references, you can add the following contents:

\bibliographystyle{plain}
\bibliography{ref}

\The bibliography {ref} command specifies the previously generated. Bib library.

The common default styles are as follows:

1 Alpha, using the first letter of the author’s name + the last two digits of the year as the label, in alphabetical order;
4. Abbrv, similar to plain, change the full spelling of the month to abbreviation, which is more compact;
5. IEEE TR, journal style of International Association of electrical and electronic engineers;
6. ACM, journal style of American Society of computer science;
7. Siam, journal style of American Society of industrial and applied mathematics;
8 Apalike, the journal style of American Psychological Society;
a

Step 5: Add Reference;

The quotation format is as follows:

\cite{Wille1982}

The content in the curly brackets is the first line of the quotation format of the related literature.

Step 6: the process of generating PDF;

1. Compile latex document with latex;

2. Compile Bib document with BibTex;

3. Using latex to compile latex documents;

4. View PDF through dvipdf.

Latex bracket size control

Various brackets are often used when editing formulas under latex. If you directly input brackets (curly brackets need to be escaped), the size is fixed. If the height of the formula is large, it will be very inconsistent.

As shown in the figure below, the brackets on the right are better than those on the left.

There are two main control methods

1. Use left and right

\Left in front of the left bracket and right in front of the right bracket.

Precautions for use

Need to pair use, can automatically control the size of different levels of brackets

Use examples

The following formula:

The corresponding latex code is:

\begin{equation}
\left \{ \frac{3}{5}  \left [ 3 + 2 * \left ( a + b \right ) \right ] \right \}
\end{equation}

2. Use the big series label

This is a series of tags, including the tag of \\\\\\\\\\\\\\\. In order, the brackets they control keep getting bigger.

Precautions for use

It doesn’t need to be used in pairs. You can control half brackets separately. The size of brackets is controlled by the specific label and can’t be adjusted automatically, so you need to pay attention to matching.

Use examples

Replace the corresponding tag in the previous example with a series of tags, as follows:

\begin{equation}
\bigg \{ \frac{3}{5}  \Big [ 3 + 2 * \big ( a + b \big ) \Big ] \bigg \}
\end{equation}

The following formula:

After a little comparison, we can find that the size of brackets is obviously different. This is because the size of brackets displayed by the left and right can be controlled automatically. It does not think it is necessary to use such large brackets, while the size of brackets displayed by the big is relatively fixed.

Therefore, it is recommended to control the size of parentheses by using both left and right

TypeError: Required argument ‘mat‘ (pos 2) not found 

Traceback (most recent call last):
  File "/Users/*******/*****.py", line 225, in <module>
    cv2.imshow(r_image)
TypeError: Required argument 'mat' (pos 2) not found

This error prompt means that the required parameter is not found, that is, the function in the code is missing the necessary parameter.

cv2.imshow()

There should be two parameters: one is the name of the image window, namely title, and the other is the pixel value matrix of the displayed image.
In addition, the data type of the matrix is np.uint8 , floating point type will display exception.
Error will be reported:

TypeError: img is not a numpy array, neither a scalar

Solution:
transform the data type

image = numpy.array(image)

Python selenium — webriver cheat sheet

Recently, I saw a webriver cheat sheet on axatrikx, which is only made in Java. I thought I could organize a python version, and I got this blog post. The main methods and key points in webriver are sorted into a table for easy reference.

Webdriver Cheat Sheet

If it helps you, or if you have any good suggestions, please let me know.

Pdf version can be downloaded here

For more articles on Python selenium, please pay attention to my CSDN column: Python selenium automated test details

Solution to the problem of vs2017 error report unable to open source file

Problem Description:

Problem Description: a new QT GUI project is created without any modification, but the error list shows that the existing file cannot be opened, and there are various red underscores under the header file of the file code, but it can be run directly main.cpp no problem.

terms of settlement:

For the existing files in the project that cannot be opened, it means that the path of the current project is not included. Here, you can refer to the acquisition method of C + + header file reference (c + + knowledge focus). So we just need to add in the current project path.
Methods: right click the project, click properties, select the included directory in VC + + directory, add $(projectdir) , then apply and confirm.

principle

#Include & lt; XX. H & gt; means to search for files directly from the function library of the compiler, and the compiler starts to search for. Xxh from the standard library path

#Include “XX. H” means to search from the user-defined file first. If not, search from the function library. The compiler starts to search XX. H from the user’s working path

If we refer to the header file written by ourselves in the way of & lt; & gt;, we will inevitably be unable to find the source file, because our file is placed in the user directory. The above solution is essentially to append the user directory to the compiler search scope. In fact, we can solve the problem by replacing & lt; & gt; with “” instead.