2. 数据类型，变量赋值和字符串格式化

  year = 2024
age = 22

print("Year:",year)
print("Age:", age)
  

  #include <stdio.h>

int main() {
	int year = 2024;
	int age = 22;

	printf("Year: %d\n", year);
	printf("Age: %d\n", age);

	return 0;
}
  

  #include <iostream>

int main()
{
	int year = 2024;
	int age = 22;

    std::cout << "Year: " << year << std::endl;
	std::cout << "Age: " << age << std::endl;
}
  

  using System;

class Program
{
    static void Main()
    {
        int year = 2024;
        int age = 22;

        Console.WriteLine("Year: " + year);
        Console.WriteLine("Age: " + age);
    }
}
  

  #include <stdio.h>

int main() {
	float pi = 3.14159265358979323846f;

	printf("Value of Pi: %.20f\n", pi);
}
  

  #include <iostream>
#include <format>

int main()
{
	float pi = 3.14159265358979323846f;

	std::cout << std::format("Value of Pi: {:.20f}",pi) << std::endl;
}
  

  using System;

class Program
{
    static void Main()
    {
        float pi = 3.14159265358979323846f;

        Console.WriteLine("Value of Pi: {0:F20}", pi);
    }
}
  

  pi = 3.14159265358979323846

print("Value of Pi: %.20f"%pi)
  

  #include <stdio.h>

int main() {
	double pi = 3.14159265358979323846;

	printf("Value of Pi: %.20f\n", pi);
}
  

  #include <iostream>
#include <format>

int main()
{
	double pi = 3.14159265358979323846;

	std::cout << std::format("Value of Pi: {:.20f}",pi) << std::endl;
}
  

  using System;

class Program
{
    static void Main()
    {
        double pi = 3.14159265358979323846;

        Console.WriteLine("Value of Pi: {0:F20}", pi);
    }
}
  

  z = 3 +4j

real_part = z.real
imaginary_part = z.imag

print(f"Complex number: {z}; Real part: {real_part}; Imaginary part: {imaginary_part}")
  

  #include <stdio.h>
#include <complex.h>

int main() {
    double complex z = 3.0 + 4.0 * I;

    double real_part = creal(z);
    double imaginary_part = cimag(z);

    printf("Complex number: %.2f + %.2fi; Real part: %f; Imaginary part: %f\n", z, real_part, imaginary_part);

    system("pause"); // 保持显示弹出的结果窗口
    return 0;
}
  

  #include <iostream>
#include <complex>

int main() {
    std::complex<double> z(3.0, 4.0);

    double real_part = z.real();
    double imaginary_part = z.imag();

    std::cout << "Complex number: " << z << "; " << "Real part: " << real_part << "; " << "Imaginary part: " << imaginary_part << std::endl;

    return 0;
}
  

  using System;
using System.Numerics;

class Program
{
    static void Main()
    {
        Complex z = new Complex(3.0, 4.0);

        double real_part = z.Real;
        double imaginary_part = z.Imaginary;

        Console.WriteLine("Complex number: {0}; Real part: {1};  Imaginary part: {2}", z, real_part, imaginary_part);
    }
}
  

  #include <stdio.h>

int main() {
    char singleChar = 'A';
    char charArray[] = "Hello C World!";

    printf("Single char: %c\n", singleChar);
    printf("Char array: %s\n", charArray);

    return 0;
}
  

  #include <iostream>

int main() {
    char singleChar = 'B';
    char charArray[] = "Hello, C++ World!";

    std::cout << "Single char: " << singleChar << "\n" << "Char array: " << charArray << std::endl;

    return 0;
}
  

  using System;

class Program
{
    static void Main()
    {
        char singleChar = 'C';
        char[] charArray = { 'H', 'e', 'l', 'l', 'o', ' ', 'C', '#', ' ', 'W', 'o', 'r', 'l', 'd', '!' };
        string charArrayAsString = new string(charArray);

        Console.WriteLine("Single char: {0} \n Char array: {1}", singleChar, charArrayAsString);
    }
}
  

  pyString = "Hello, Python World!"

print("String: ", pyString)
  

  #include <iostream>
#include <string>

int main() {
    char cString[] = "Hello, C++ World!";
    std::string cppString = "Hello, C++ World!";

    std::cout << "C-style string: " << cString << "\n" << "std::string: " << cppString << std::endl;

    return 0;
}
  

  using System;

class Program
{
    static void Main()
    {
        string csString = "Hello, C# World!";

        Console.WriteLine("String: " + csString);
    }
}
  

  is_true = True
is_false = False

if is_true:
    print("The condition is true.")
if not is_false:
    print("The condition is false.")
  

  #include <stdio.h>
#include <stdbool.h>

int main() {
    bool isTrue = true;
    bool isFalse = false;

    if (isTrue) {
        printf("The condition is true.\n");
    }
    if (!isFalse) {
        printf("The condition is false.\n");
    }
    
    return 0;
}
  

  #include <iostream>

int main() {
    bool isTrue = true;
    bool isFalse = false;

    if (isTrue) {
        std::cout << "The condition is true." << std::endl;
    }
    if (!isFalse) {
        std::cout << "The condition is false." << std::endl;
    }
        
    return 0;
}
  

  using System;

class Program
{
    static void Main()
    {
        bool isTrue = true;
        bool isFalse = false;

        if (isTrue)
        {
            Console.WriteLine("The condition is true.");
        }
        if (!isFalse)
        {
            Console.WriteLine("The condition is false.");
        }
    }
}
  

  #include <stdio.h>

void printMessage() {
    printf("Hello World!\n");
}

int main() {
    printMessage();

    return 0;
}
  

  #include <iostream>

void printMessage() {
    std::cout << "Hello World!" << std::endl;
}

int main() {
    printMessage();
        
    return 0;
}
  

  using System;

class Program
{
    static void printMessage()
    {
        Console.WriteLine("Hello, World!");
    }

    static void Main()
    {
        printMessage();
    }
}
  

  a = -32768      
b = 65535               
c = -2147483648            
d = 4294967295            
e = -9223372036854775808  
f = 1000000000000000000001 # 仅受可用内存的约束

print(a,b,c,d,e,f)
  

  #include <stdio.h>

int main() {
	signed int a = -10;
	unsigned int b = 10;
	short int c = 32767;
	long int d = 2147483647;
	unsigned long int e = 4294967295;

	printf("%d,%u,%d,%ld,%lu", a, b, c, d, e);

	return 0;
}
  

  #include <iostream>
#include <format>

int main() {
	signed int a = -10;
	unsigned int b = 10;
	short int c = 32767;
	long int d = 2147483647;
	unsigned long int e = 4294967295;

	std::cout << std::format("{},{},{},{},{}", a,b,c,d,e) << std::endl;
        
    return 0;
}
  

  using System;

class Program
{
    static void Main()
    {
        short a = -32768;               // short, 16-bit signed integer
        ushort b = 65535;               // ushort, 16-bit unsigned integer
        int c = -2147483648;            // int, 32-bit signed integer
        uint d = 4294967295;            // uint, 32-bit unsigned integer
        long e = -9223372036854775808;  // long, 64-bit signed integer
        ulong f = 18446744073709551615; // ulong, 64-bit unsigned integer

        Console.WriteLine("{0},{1},{2},{3},{4},{5}", a,b,c,d,e,f);
    }
}
  

  #include <iostream>
#include <format>
#include <typeinfo>

int main()
{
	auto x = 3.14;
	auto y = 42;
	auto name = "Alice";

	std::cout << std::format("{}:{}\n{}:{};\n{}:{}", typeid(x).name(),x, typeid(y).name(),y, typeid(name).name(),name) << std::endl;
}
  

  using System;

class Program
{
    static void Main()
    {
        var x = 3.14;
        var y = 42;
        var name = "Alice";

        Console.WriteLine("{0}:{1}\n{2}:{3};\n{4}:{5}", x.GetType(),x,y.GetType(), y,name.GetType(), name);
    }
}
  

  using System;

class Program
{
    static void Main()
    {
        int x = 10;
        object obj = x;     // Boxing: x is boxed into obj
        int y = (int)obj;   // Unboxing: obj is unboxed back into an int

        object objStr = "Hello";
        object objDouble = 3.14;

        Console.WriteLine("{0}:{1}\n{2}:{3}\n{4}:{5}\n{6}:{7}\n{8}:{9}", 
            x.GetType(), x, obj.GetType(), obj, y.GetType(), y, objStr.GetType(), objStr, objDouble.GetType(), objDouble);
    }
}
  

  print("%s says: %d/%d is %.3f." % ("John", 2, 3, 2/3))
print("Hex: %(hex)x, Octal: %(octal)7o" % {"hex":255,"octal":255})
  

  #include <stdio.h>

int main() {
	printf("%s says: %d/%d is %.3f.\n", "John", 2, 3, 2.0 / 3.0);
	printf("Hex: %x, Octal: %7o", 255, 255);

	return 0;
}
  

  #include <iostream>

int main()
{
	printf("%s says: %d/%d is %.3f.\n", "John", 2, 3, 2.0 / 3.0);
	printf("Hex: %x, Octal: %7o", 255, 255);

	return 0;
}
  

  print("{:s} says: {:d}/{:d} is {:.3f}.".format("John", 2, 3, 2/3))
print("Hex: {hex:x}, Octal: {octal:7o}".format(hex=255,octal=255))

print("-"*50)

template='{{name}}:{0},category:{1},score:{2}'
print(template.format('湘村菜馆','美食_中餐厅',4))

template='name:{},category:{},score:{}'
print(template.format('湘村菜馆','美食_中餐厅',4))

template='name:{name},category:{category},score:{score}'
print(template.format(name='湘村菜馆',category='美食_中餐厅',score=4))

info_dict={'name':'湘村菜馆','category':'美食_中餐厅','score':4}
template='name:{0[name]},category:{0[category]},score:{0[score]}'
print(template.format(info_dict))

template='name:%(name)s,category:%(category)s,score:%(score)s'
print(template%dict(name='湘村菜馆',category='美食_中餐厅',score=4))

template='name:{0},category:{category},score:{score}'
print(template.format('湘村菜馆',category='美食_中餐厅',score=4))

import sys
print('My {1[name]} runs {0.platform}.'.format(sys,{'name':'Omen'}))

info_lst=['湘村菜馆','美食_中餐厅']
print('name:{0[0]},category:{0[1]},score:{1}'.format(info_lst,4))
  

  #include <iostream>
#include <format>

int main()
{
	std::cout << std::format("{:s} says: {:d} / {:d} is {:.3f}.", "John", 2, 3, 2.0 / 3.0) << std::endl;
	std::cout << std::format("Hex: {0:x}, Octal: {1:7o}",255, 255) << std::endl;

	std::cout << std::string(30, '-') << std::endl;

	std::cout << std::format("{} {}: {}!\n", "Hello", "World", 2024);
	std::cout << std::format("{1} {0}: {2}!\n", "World", "Hello", 2024);
	std::cout << std::format("{0} {1}: {0} {2}!\n", "Hello", "World", 2024);
	std::cout << std::format("{0} {2}!\n", "Hello", "World", 2024);

	return 0;
}
  

  using System;

class Program
{
    static void Main()
    {
        Console.WriteLine(String.Format("{0} says: {1:d} / {2:d} is {3:f3}.", "John", 2, 3, 2.0 / 3.0));
        Console.WriteLine(String.Format("Hex: {0:x}, Octal: {1:7d}", 255, Convert.ToString(255,8)));
        Console.WriteLine("Hex: {0:x}, Octal: {1:7d}", 255, Convert.ToString(255, 8));

        Console.WriteLine(new String('-', 50));
        Console.WriteLine(String.Format("Scientific: {0:E}", 157));        
        Console.WriteLine(String.Format("Percent: {0:P}", 0.157));
        Console.WriteLine(String.Format("Currency: {0:C}", 157));

        System.Globalization.CultureInfo culture = new System.Globalization.CultureInfo("en-US");
        Console.WriteLine(String.Format(culture,"Currency: {0:C}", 157));
    }
}
  

  def square(x):
    return x * x

num1 = 12.34567
num2 = 7
precision = 2

result = f"The sum of {num1:.2f} and {num2} is {(num1 + num2):.{precision}f}.\n The square of {num2} is {square(num2)}."

print(result)
  

  using System;

class Program
{
    static double square(double x)
    {
        return x * x; 
    } 
    static void Main()
    {
        double num1 = 12.34567;
        double num2 = 7;

        string output = $"The sum of {num1:F2} and {num2} is {(num1 + num2):F2}.\n The square of {num2} is {square(num2)}.";
        Console.WriteLine(output);
    }
}