Category：C
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Time：2021-7-31
Compared with 30 years ago, programmers in the Internet era now have many subdivision R & D directions, such as front-end, back-end, algorithm, desktop software, artificial intelligence, etc. Different subdivision directions also have different requirements. But no matter what direction you choose, a good programmer should have the following five abilities. C/C++Learning skirt【seven one […]
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Time：2021-7-31
Right click your project to open properties > C / C + + > language > C + + language standard, select c + + 17 or C + + latest. Step 1: right click the item, as shown in the figure below: Step 2: select the lowest “attribute” item, as shown in the following […]
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Time：2021-7-30
QT serial communication foundation and terminology description The concept of serial communications is very simple. The serial port sends and receives bytes by bit. Although it is slower than parallel communication by byte, the serial port can use one line to send data and another line to receive data. It is very simple and can […]
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Time：2021-7-30
Union, Chinese name “union, common body”, is a data structure similar to the structure struct to some extent. The common body (Union) and structure (struct) can also contain many data types and variables. But in Union, Each member shares a memory space, and the length of a joint variable is equal to the longest […]
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Time：2021-7-29
Today, I’ll take you to review a forgotten C language knowledge point, the storage of negative numbers and a typical investigation form. Let’s look at a topic first #include int main() { int a,b,c,d; // perhaps int a,b,c,d; a=0x8; b=a>>1; c=~(~0<<1); d=b&c; printf(“c is %d\n”,c); printf(“d is %d\n”,d); } Resolution: Suppose the computer is storing eight […]
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Time：2021-7-29
Previously, I wrote the interface for the upper computer to do basic transceiver, which is equivalent to a serial port assistant. First map: As a serial port assistant, the function is relatively perfect. There are five sending slots and one receiving slot, which can detect the available serial ports and add relevant signs, serial port […]
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Time：2021-7-28
The original is from WeChat official account: Jing Yu. The rotation array is divided into left rotation and right rotation. The force buckle 189 is entitled right rotation, and today’s share is left rotation. Given an array, rotate the elements in the array to the leftkLocations, wherekIs a nonnegative number. Figure 0-1 array arr […]
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Time：2021-7-28
I mainly use the serial port class here. The function is to open the serial port in read-write mode, click the send data button to send the data in the sending area to the buffer, and then display it in the receiving area. The interface is as follows: (the source code can be downloaded here) […]
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Time：2021-7-27
When using serial port to receive data, incomplete data reception will occur when the amount of data is large. Because the serial port data acquisition function readall() is triggered by the readyread() signal, but the readyread() signal is sent immediately when the serial port reads the start flag, which is not guaranteed to be the […]
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Time：2021-7-26
Recently, I read the self cultivation of programmers – links, loading and library. I felt that when I first learned C, I didn’t have a clear understanding of external, static and other keywords. Therefore, I reviewed the relevant parts about scope, link attributes and storage types in C and pointers, added my own understanding, and […]
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Time：2021-7-26
Recently, I received a demand to beautify QT qchart curve, draw a broken line diagram, use hollow dots to mark the key points, and move the mouse to the key points to display the current value; Move the mouse away and the value disappears. The renderings are as follows: When we meet this demand, we […]
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Time：2021-7-24
1. Byte alignment (memory dependent) In modern computers, the memory space is divided according to bytes. Theoretically, it seems that the access to any type of variables can start from any address, but the actual situation is that when accessing a specific variable, it is often accessed at a specific memory address, which requires various […]
