1.1 What’s the CMake?#

CMake is an open-source, cross-platform family of tools designed to build, test and package software. CMake is used to control the software compilation process using simple platform and compiler independent configuration files, and generate native makefiles and workspaces that can be used in the compiler environment of your choice.

CMake needs CMakeLists.txt to run properly.

A CMakeLists.txt consists of commands , comments and spaces.

• The commands include command name, brackets and parameters , the parameters are separated by spaces. Commands are not case sensitive.
• Comments begins with #.

Steps for generating a makefile and compiling on Linux using CMake:

Step1: Writes the CMake configuration file CMakeLists.txt.

Step2: Executes the command cmake PATH to generate the Makefile.(PATH is the directory where the CMakeLists.txt resides.)

Step3: Compiles using the make command.

1.2 A single source file in a project#

The most basic project is an executable built from source code files. For simple projects, a three-line CMakeLists.txt file is all that is required.

cmake_minimum_required(VERSION 3.10)
#usa cmake --version in Vscode terminal window to check the cmake version in your computer.

add_executable(Hello hello.cpp)
#Adds the Hello executable target which will be built from hello.cpp

In current directory, type cmake . to generate makefile. If cmake does not be installed, follow the instruction to install cmake.

1.3 Multi-source files in a project#

Yep, you just need to appendix to the rear the files’ name.

aux_source_directory(. DIR_SRCS)
#stores all files in the current directory into the variable DIR_SRCS.

add_executable(hello ${DIR_SRCS})
# add_executable(hello main.cpp factorial.cpp printhello.cpp)  ERROR
# add_executable(hello src/main.cpp src/factorial.cpp src/printhello.cpp)  right relative path~

./CmakeDemo3
│
├── src/
│   ├── main.cpp
│   └── function.cpp
│
└── include/
    └── function.h

aux_source_directory(./src DIR_SRCS)
# aux_source_directory(<dir> <variable>)

2.1 Command-Line Arguments#

• At the beginning of program execution, arguments are read.
• All the arguments here are treated as string.
• Suitable for scenarios involving scripts and tools, but lacks interactivity.

#include <stdio.h>   // c_a_demo.c

int main(int argc, char*argv[]){
    if(argc ==1)
        printf("ONLY argv[0]:%s\n",argv[0]);
    else
        for(int i=0;i<argc;i++)
            printf("argv[%d]: %s\n",i, argv[i]);

    return 0;
}

2.2 Standard Input#

• During program execution, read input data from standard input devices.
• Support different types of input data.
• Suitable for interacting with users.

#include <stdio.h>

int main(int argc, char*argv[]){
    char uname[10]={""};
    char dname[10]={""};
    char cname[10]={""};
    printf("please input the name of University: ");
    scanf("%s", uname); 
    printf("please input the name of department: ");
    scanf("%s", dname);
    printf("please input the name of course: ");
    scanf("%s", cname);     
    printf("uname: %s, dname: %s, cname:%s\n",uname,dname,cname);  
    return 0;
}

#include <stdio.h>

int main(){
    int prj_id=0;
    float prj_sc=0.0f;
    char valid=0;
    printf("please input 'project id' in decimal int: ");
    scanf("%d", &prj_id); 
    printf("please input the score : ");
    scanf("%f", &prj_sc);
    printf("please input the score is valid or not(Y/N): ");
    while (getchar() != '\n');
    scanf("%c", &valid);     
    printf("project id: %d, score: %.1f, %s\n",
               prj_id, prj_sc, (valid=='y'||valid=='Y')?"VALID":"NOT VALIDE" );  
    return 0;
}

2.3 others inputs source#

Besides reading data from standard input (typically the keyboard), C++ programs can also obtain input from the following sources:

• Files: Data can be read from files using file stream classes such as ifstream. This allows programs to process data stored in various file formats.

• Network: Input can be received from remote servers or clients through network sockets. This involves network programming, which can use libraries like Boost.Asio or other networking libraries to handle TCP/IP communication.

• GUI (Graphical User Interface): User input can be gathered through GUI elements such as text boxes, buttons, and sliders. This typically involves using GUI frameworks like Qt, GTK, or WxWidgets to create and manage the graphical interface.

• Database: Data can be retrieved from databases using database connections and queries. This often requires database-specific libraries or connectors, such as ODBC, MySQL Connector, or SQLite, to interact with the database server.

• Sensors: Input can be acquired from physical sensors through hardware interfaces. This may involve using specific hardware drivers or APIs provided by the sensor manufacturer to communicate with and retrieve data from the sensors.

Each of these input methods may require additional setup and configuration, as well as the inclusion of appropriate libraries or frameworks in your C++ project to handle the input operations effectively.

3.1.Data storage on construction type#

#include<iostream>
#include<cstring>
using namespace std;

int main(){
    char SC[ ]="SUSTECH";
    char sc[ ]= {'s','u','s','t','e','c','h'};

    printf("size of SC: %ld bytes, sc: %ld\n",sizeof(SC), sizeof(sc));

    return 0;
}

#include<stdio.h>
struct data{
    int a;
    char c;
};

int main(){
    struct data icx;
    icx.a = 0x11223344;
    icx.c = 0x56;

    printf("size of icx: %ld\n",sizeof(icx));
    printf("size of icx.a: %ld, icx.a=0x%x\n",sizeof(icx.a),icx.a);
    printf("size of icx.c: %ld, icx.c=0x%x\n",sizeof(icx.c),icx.c);
    return 0;
}

#include<stdio.h>
union data
{
    int a;
    char c;
};

int main()
{
    union data endian;
    endian.a = 0x11223344;
    endian.c = 0x56;

    printf("size of endian: %ld\n",sizeof(endian));
    printf("size of endian.a: %ld,endian.a=0x%x\n",sizeof(endian.a),endian.a);
    printf("size of endian.c: %ld,endian.c=0x%x\n",sizeof(endian.c),endian.c);

     return 0;
}

4.1 Exercise#

Please refer to the content of courseware to generate a makefile using cmake tool and CMakeLists.txt, run the makefile to generate an executable file, and then run the executable file.

NOTE

All the source files are in ./src , all the head files are in ./inc, all the build files are in ./build.

# CMake minimum required version
cmake_minimum_required(VERSION 3.10)

# project information,也就是最后生成的可执行文件名称
project(hello)

# Search the source files in the src directory
# and store them into the variable DIR_SRCS
aux_source_directory(./src DIR_SRCS)

# aux_source_directory(<dir> <variable>)
# 将src目录下的所有源文件存储到变量DIR_SRCS中

# add the directory of include files
include_directories(./include)


# 添加可执行文件
add_executable(hello ${DIR_SRCS})
# add_executable(hello main.cpp factorial.cpp printhello.cpp)  ERROR
# add_executable(hello src/main.cpp src/factorial.cpp src/printhello.cpp)  right relative path~

4.2 Exercise#

First, complete the code, then run the program, explain the result and answer the following question to SA. If it has bugs, fix them.

#include <iostream>
#include <string.h>
using namespace std;
int main()
{
    int cards[4]{};
    int hands[4];
    int price[] = {2.8,3.7,5,9,`C`, `D`}; 
    char direction[4] {'L',82,'U',68};
    char title[] = "DeepSeek is an awesome tool.";   
    cout << "sizeof(cards) = " << sizeof(cards) << ",sizeof of cards[0] = " << sizeof(cards[0]) << endl;
    cout << "sizeof(price) = " << sizeof(price) << ",sizeof of price[0] = " << sizeof(price[0]) << endl;
    cout << "sizeof(direction) = " << sizeof(direction) << ",length of direction = " << strlen(direction) << endl;
    cout << "sizeof(title) = " << sizeof(title) << ",length of title = " << strlen(title) << endl;

    return 0;
}

Q. It is asked to get the the number of characters in dirction(which should be 4) by using strlen without changing the size of the dirction array, one option is to add a piece of code between the definitions on dirction and title:

Here’s a different implementation of my original code, modifying some details: I change the data-type of the price[] and add the ‘\0’ in the last of direction[].

float price[] = {2.8,3.7,5,9,'C', 'D'}; 
char direction[]= {'L',82,'U',68,'\0'};

4.3 Exercise#

#include <stdio.h>  //p2.c
union data{
    int n;
    char ch;
    short m;
};
int main(){
    union data a;
    printf("%d, %d\n", sizeof(a), sizeof(union data) );
    a.n = 0x40;
    printf("%X, %c, %hX\n", a.n, a.ch, a.m);
    a.ch = '9';
    printf("%X, %c, %hX\n", a.n, a.ch, a.m);
    a.m = 0x2059;
    printf("%X, %c, %hX\n", a.n, a.ch, a.m);
    a.n = 0x3E25AD54;
    printf("%X, %c, %hX\n", a.n, a.ch, a.m);

    return 0;
}

Run the program and explain the result to SA.

Just compile the file, we see the question:

So let’s change %d to %zu or %ld. The cause of the compilation error requires that the inputs format match the output format.

4.4 Exercise#

#include <iostream>
using namespace std;
enum Day{/*complete code here if needed*/};
enum Weather{/*complete code here if needed*/};

int main( /*complete code here if needed*/ ){
    int d=0;
    int w=0;
    cout<<"input the Day value:
 Monday(1), Tuesday(2), Wednesday(3), Thursday(4), 
Friday(5), Saturday(6), Sunday(7)\n";
   /*complete code here if needed*/

    cout<<"This is"<</*complete code here if needed*/<<endl;

    cout<<"input the Weather value: SUNNY(0), RAINY(1), CLOUDY(2), SNOWNY(3)\n";
     /*complete code here if needed*/

    cout<<"The weather is: "<< /*complete code here if needed*/;

   if(/*complete code here if needed*/) cout<<"can Travel\n";
    else cout<<"not suitable for travelling\n"; 
    return 0;
}

1. Design two enumeration types. The first is an enum Day for (Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, Sunday), and the second is an enum Weather for (SUNNY, RAINY, CLOUDY, SNOWNY).

2. Complete the main function, which ask user to input the day value and the weather value accoding to the notice information, if the day is at weekend and the weather is SUNNY, pring out can Travel, else print out not suitable for travelling.

Above the code is my Implement:

#include <iostream>
using namespace std;
enum Day{
    Monday = 1, Tuesday = 2, Wednesday = 3, Thursday = 4, 
    Friday = 5, Saturday = 6, Sunday = 7
};
enum Weather{    SUNNY = 0, RAINY = 1, CLOUDY = 2, SNOWY = 3};

int main() {
    int d = 0;
    int w = 0;

    // 提示用户输入星期值
    cout << "Input the Day value: Monday(1), Tuesday(2), Wednesday(3), Thursday(4), "
         << "Friday(5), Saturday(6), Sunday(7)\n";
    cin >> d;

    // 根据输入的星期值输出对应的星期名称
    cout << "This is ";
    switch (d) {
        case Monday:    cout << "Monday"; break;
        case Tuesday:   cout << "Tuesday"; break;
        case Wednesday: cout << "Wednesday"; break;
        case Thursday:  cout << "Thursday"; break;
        case Friday:    cout << "Friday"; break;
        case Saturday:  cout << "Saturday"; break;
        case Sunday:    cout << "Sunday"; break;
        default:        cout << "Invalid Day"; break;
    }
    cout << endl;

    // 提示用户输入天气值
    cout << "Input the Weather value: SUNNY(0), RAINY(1), CLOUDY(2), SNOWY(3)\n";
    cin >> w;

    // 根据输入的天气值输出对应的天气名称
    cout << "The weather is: ";
    switch (w) {
        case SUNNY:   cout << "Sunny"; break;
        case RAINY:   cout << "Rainy"; break;
        case CLOUDY:  cout << "Cloudy"; break;
        case SNOWY:   cout << "Snowy"; break;
        default:      cout << "Invalid Weather"; break;
    }
    cout << endl;

    // 判断是否适合出行
    if ((d >= Monday && d <= Friday && w == SUNNY) || (d == Saturday && w != RAINY) || (d == Sunday && w != RAINY)) {
        cout << "Can travel\n";
    } else {
        cout << "Not suitable for travelling\n";
    }

    return 0;
}

We could use the command to invoke the main function

echo 6 0 | ./a.out