0000 0000 000000010000
0000 0001 000000000001
0001 0001 000000010000
0001 0001 000000000001

#include<stdio.h>
int main(){
    printf("Hello, world\n");
    return 0;
}

#include<stdio.h>
int main(){
    printf("Hello, world\n");
    return 0;
}

#include<iostream>
int main(){
    std::cout << "Hello, world" << std::endl;
    return 0;
}

print("Hello, world\n")

public class HelloWorld {
    public static void main(String[] args) {
        System.out.println("hello, world!");
    }
}

g++ --version

g++ (Rev10, Built by MSYS2 project) 12.2.0
Copyright (C) 2022 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

wsl --install

sudo apt upgrade
sudo apt install g++ gdb
code .

#include<iostream>
int main(){
    std::cout << "hello, world\n";
    return 0;
}

int a = 1; //外層變數
{
    int a = 2; //內層變數
}
a = 3;//到這裡{}裡的a就沒有作用了，修改的是外層的那個

std::ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0); 

int a=3, b=5;
printf("%d %d", a, b);

int a=5;
printf("%p", &a);

int hr, min;
scanf("%d:%d", &hr, &min);

int a, b;
scanf("%2d%2d", &a, &b);

#include <iostream>
int main(){
    int a, b;
    cin >> a >> b;
    cout << a << ' ' << b << '\n';
    return 0;
}

#include <stdio.h>
int main(){
    int a, b;
    scanf("%d%d", &a, &b);
    printf("%d %d", a, b);
    return 0;
}

#include<iostream>
using namespace std;
int main(){

    int *a = new int;
    cout << a << '\n'; //0xbe1560

    int b = 5;
    int *c = &b;
    cout << c << ' ' << *c; //0x70fdfc 5
    return 0;
}

#include<iostream>
using namespace std;
int main(){
    int data[5][5];
    for(int i=0;i<5;i++){
        for(int j=0;j<5;j++){
            data[i][j]=i*5+j;
        }
    }
    /*
    {
        { 0,  1,  2,  3,  4},
        { 5,  6,  7,  8,  9},
        {10, 11, 12, 13, 14},
        {15, 16, 17, 18, 19},
        {20, 21, 22, 23, 24}
    }
    */
    cout << *(*(data+2)+3); //13
    return 0;
}

#include <iostream>
using namespace std;
int main() {
    int a = 5;
    int &b = a;
    b = 1;
    cout << a; //1
    return 0;
}

// do something

if(condition){
    // do something if true
}
else{
    // do something if false
}

// do something

// ...

if(condition1){
    //...
}
else{
   if(condition2){
       // ...
   }
   else{
       // ...
   }
}

// ...

// ...

if(condition1){
    // ...
}
else if(condition2){
    // ...
}
else{
    // ...
}

// ...

b=a>0?a:(-a);

// ...
while(condition){
    // ...
}
// ...

// ...
while(cin >> n){
    // ...
}
// ...

// ...
for(初始化; 持續條件; 常駐步驟){
    // ...
}
// ...

// ...
for(int i=0; i<n; i++){
    // ...
}
// ...

while(true){
    // ...
}

//範例：如果輸入=0就跳出
int n;
while(true){
    cin >> n;
    if(n==0) break;
    // ...
}
//也可以寫成
int n;
while(cin >> n && n!=0){
    // ...
}

//範例：輸出輸入的數字
//除非輸入=48763則跳過
int n;
while(true){
    cin >> n;
    if(n==48763) continue;
    cout << n << '\n';
    // ...
}

#include<iostream>
using namespace std;
int main(){
    int data[5][5];
    for(int i=0;i<5;i++){
        for(int j=0;j<5;j++){
            data[i][j]=i*5+j;
        }
    }
    /*
    {
        { 0,  1,  2,  3,  4},
        { 5,  6,  7,  8,  9},
        {10, 11, 12, 13, 14},
        {15, 16, 17, 18, 19},
        {20, 21, 22, 23, 24}
    }
    */
    cout << *(*(data+2)+3); //13
    return 0;
}

do{
    // ...
} while(condition);

int a[]={0, 1, 2, 3, 4};
for(int i:a) i=0;
for(int i:a) cout << i << ' '; // 0, 1, 2, 3, 4

int a[]={0, 1, 2, 3, 4};
for(int& i:a) i=0;
for(int i:a) cout << i << ' '; // 0, 0, 0, 0, 0

#include <iostream>
#define int unsigned long long
using namespace std;
signed main() {
    int n, m;
    cin >> n >> m;
    int dp[n + 1];
    for (int i = 0; i <= n; i++) dp[i] = 0;
    dp[0] = 1;
    dp[1] = 1;
    int temp;
    for (int l = 1; l < m; l++) {
        temp = dp[0];
        for (int j = 1; j <= n; j++) dp[0] += dp[j];
        for (int j = n; j >= 2; j--) dp[j] = dp[j - 1];
        dp[1] = temp;
    }
    int ans = 0;
    for (int i = 0; i <= n; i++) ans += dp[i];
    cout << ans;
    return 0;
}

//字串預處理
#include <iostream>
#include <string>
using namespace std;
int main() {
    string temp;
    for (auto &i : "A .- B -... C -.-. D -.. E . F ..-. G --. H ....I .. J .--- K -.- L .-..M -- N -. O --- P .--.Q --.- R .-. S ... T -U ..- V ...- W .-- X -..-Y -.-- Z --..") {
    if (i == ' ') continue;
    if ('A' <= i && i <= 'Z') cout << "\"" << temp << "\", \n", temp = "";
    else temp += i;
    }
    return 0;
}

#include <iostream>
#include <string>
using namespace std;
int main() {
    const string table[26] = {
        ".-",
        "-...",
        "-.-.",
        "-..",
        ".",
        "..-.",
        "--.",
        "....",
        "..",
        ".---",
        "-.-",
        ".-..",
        "--",
        "-.",
        "---",
        ".--.",
        "--.-",
        ".-.",
        "...",
        "-",
        "..-",
        "...-",
        ".--",
        "-..-",
        "-.--"};
    string input;
    cin >> input;
    string ans;
    for (unsigned int i = 0; i < input.size(); i++) {
        ans += table[input[i] - 'A'];
    }
    cout << ans;
    return 0;
}

#include<iostream>
using std::cout;
void swap(int &a, int &b){
    int temp=a;
    a=b;
    b=temp;
    return;
}
int main() {
    int a = 5, b = 3;
    swap(a, b);
    cout << a << ' ' << b; // 3 5
    return 0;
}

int fibonacci(int n) {
    if (n == 1 || n == 2) return 1;
    return fibonacci(n - 1) + fibonacci(n - 2);
}

#include <iostream>
using namespace std;
struct person {
    double height, weight;
    double BMI() {
        return weight / (height * height);
    }
};
int main() {
    person Sea;
    Sea.height = 1.813;
    Sea.weight = 71.4;
    cout << Sea.BMI();	// 21.7221
}

struct person {
    double height, weight;
    double BMI();
};
double person::BMI(){
    return person::weight/(person::height*person::height);
}

struct person {
    double height, weight;
    struct other{
        double length_of_hair;
        string favorate_food;
    } other_information;
};

struct complex{
    int a, b;
    complex(int _a, int _b){
        a=_a;
        b=_b;
    }
};
int main(){
    complex number(125, 807);
    cout << number.a << ' ' << number.b; // 125 807
    return 0;
}

struct complex {
    int a, b;
    complex(int _a, int _b) {
        a = _a;
        b = _b;
    }
    complex operator+(complex another) {
        return {a + another.a, b + another.b};
    }
};
int main() {
    complex number1(125, 807), number2(123, 456);
    complex sum = number1 + number2;
    cout << sum.a << ' ' << sum.b;
    return 0;
}