運(yùn)算符和字符串操作在程序設(shè)計中非常常用。本篇文章將會從多個方面闡述這一主題。

一、運(yùn)算符

運(yùn)算符是一種用來執(zhí)行特定數(shù)學(xué)或邏輯運(yùn)算的符號。Python中的運(yùn)算符包括：算數(shù)運(yùn)算符、比較運(yùn)算符、賦值運(yùn)算符、邏輯運(yùn)算符、位運(yùn)算符等多種類型。

1.1 算數(shù)運(yùn)算符

算數(shù)運(yùn)算符是最基本的運(yùn)算符之一，它們用于執(zhí)行基本的算術(shù)操作，如加、減、乘、除等。

a = 10
b = 3
print("a + b =", a + b)   # 輸出a + b = 13
print("a - b =", a - b)   # 輸出a - b = 7
print("a * b =", a * b)   # 輸出a * b = 30
print("a / b =", a / b)   # 輸出a / b = 3.3333333333333335
print("a // b =", a // b) # 輸出a // b = 3
print("a % b =", a % b)   # 輸出a % b = 1
print("a ** b =", a ** b) # 輸出a ** b = 1000

1.2 比較運(yùn)算符

比較運(yùn)算符用于比較兩個變量的值，并返回一個布爾值（True或False）。

a = 10
b = 5
print("a > b =", a > b)   # 輸出a > b = True
print("a < b =", a < b)   # 輸出a < b = False
print("a == b =", a == b) # 輸出a == b = False
print("a != b =", a != b) # 輸出a != b = True
print("a >= b =", a >= b) # 輸出a >= b = True
print("a <= b =", a <= b) # 輸出a <= b = False

1.3 賦值運(yùn)算符

賦值運(yùn)算符用于將右邊的值賦給左邊的變量。

a = 10
b = 5
c = a + b
print("c =", c)          # 輸出c = 15
a += b
print("a += b：a =", a)  # 輸出a += b：a = 15
a -= b
print("a -= b：a =", a)  # 輸出a -= b：a = 10
a *= b
print("a *= b：a =", a)  # 輸出a *= b：a = 50
a /= b
print("a /= b：a =", a)  # 輸出a /= b：a = 10.0
a %= b
print("a %= b：a =", a)  # 輸出a %= b：a = 0.0
a **= b
print("a **= b：a =", a) # 輸出a **= b：a = 0.0

1.4 邏輯運(yùn)算符

邏輯運(yùn)算符用于組合多個條件，并返回一個布爾值。

a = 10
b = 5
c = 3
print("a > b and b > c =", a > b and b > c) # 輸出a > b and b > c = True
print("a > b or b < c =", a > b or b < c)   # 輸出a > b or b < c = True
print("not a > b =", not a > b)              # 輸出not a > b = False

1.5 位運(yùn)算符

位運(yùn)算符是用來執(zhí)行位運(yùn)算的運(yùn)算符。

a = 10
b = 5
print("a & b =", a & b)     # 輸出a & b = 0
print("a | b =", a | b)     # 輸出a | b = 15
print("a ^ b =", a ^ b)     # 輸出a ^ b = 15
print("~a =", ~a)           # 輸出~a = -11
print("a << 2 =", a << 2)   # 輸出a << 2 = 40
print("a >> 2 =", a >> 2)   # 輸出a >> 2 = 2

二、字符串操作

字符串是程序中常用的數(shù)據(jù)類型之一。在Python中，字符串可以使用單引號、雙引號或三引號來表示。字符串操作是對字符串進(jìn)行操作的一些方法，包括格式化、拆分、連接、替換、大小寫轉(zhuǎn)換等。

2.1 字符串格式化

字符串格式化是指將變量的值插入到占位符中，以便動態(tài)生成字符串。

name = "Tom"
age = 18
print("My name is %s, I am %s years old." % (name, age)) # 輸出My name is Tom, I am 18 years old.

2.2 字符串拆分

字符串拆分是指將字符串按照指定的分隔符進(jìn)行拆分。

string = "a,b,c,d,e"
list = string.split(",")
print(list) # 輸出['a', 'b', 'c', 'd', 'e']

2.3 字符串連接

字符串連接是指將多個字符串拼接成一個字符串。

string1 = "hello"
string2 = "world"
string = string1 + " " + string2
print(string) # 輸出hello world

2.4 字符串替換

字符串替換是指將字符串中的某些字符替換成其他字符。

string = "hello world"
new_string = string.replace("world", "Python")
print(new_string) # 輸出hello Python

2.5 字符串大小寫轉(zhuǎn)換

字符串大小寫轉(zhuǎn)換是指將字符串中的字母大小寫進(jìn)行轉(zhuǎn)換。

string = "Hello World"
lower_string = string.lower()
upper_string = string.upper()
print(lower_string) # 輸出hello world
print(upper_string) # 輸出HELLO WORLD

三、Java程序中常用的運(yùn)算符和字符串操作

Java語言是一種廣泛使用的面向?qū)ο缶幊陶Z言，同樣也包含了多種運(yùn)算符和字符串操作。

3.1 運(yùn)算符

Java中的運(yùn)算符和Python中的運(yùn)算符類似，包括算數(shù)運(yùn)算符、比較運(yùn)算符、賦值運(yùn)算符、邏輯運(yùn)算符、位運(yùn)算符等多種類型。

3.2 字符串操作

Java中的字符串操作與Python中的字符串操作也非常相似，包括字符串格式化、拆分、連接、替換、大小寫轉(zhuǎn)換等。

3.3 代碼示例

public class Main {
  public static void main(String[] args) {
    // 算數(shù)運(yùn)算符
    int a = 10;
    int b = 3;
    System.out.println("a + b = " + (a + b));   // 輸出a + b = 13
    System.out.println("a - b = " + (a - b));   // 輸出a - b = 7
    System.out.println("a * b = " + (a * b));   // 輸出a * b = 30
    System.out.println("a / b = " + (a / b));   // 輸出a / b = 3
    System.out.println("a % b = " + (a % b));   // 輸出a % b = 1
    System.out.println("a += b：a = " + (a += b)); // 輸出a += b：a = 13
    System.out.println("a -= b：a = " + (a -= b)); // 輸出a -= b：a = 10
    System.out.println("a *= b：a = " + (a *= b)); // 輸出a *= b：a = 30
    System.out.println("a /= b：a = " + (a /= b)); // 輸出a /= b：a = 10
    System.out.println("a %= b：a = " + (a %= b)); // 輸出a %= b：a = 1

    // 比較運(yùn)算符
    int c = 5;
    System.out.println("a > b = " + (a > b));   // 輸出a > b = true
    System.out.println("a < b = " + (a < b));   // 輸出a < b = false
    System.out.println("a == b = " + (a == b)); // 輸出a == b = false
    System.out.println("a != b = " + (a != b)); // 輸出a != b = true
    System.out.println("a >= b = " + (a >= b)); // 輸出a >= b = true
    System.out.println("a <= b = " + (a <= b)); // 輸出a <= b = false

    // 邏輯運(yùn)算符
    System.out.println("a > b && b > c =" + (a > b && b > c)); // 輸出a > b && b > c = true
    System.out.println("a > b || b < c =" + (a > b || b < c));   // 輸出a > b || b < c = true
    System.out.println("!(a > b) =" + !(a > b));                // 輸出!(a > b) = false

    // 位運(yùn)算符
    int d = 5;
    System.out.println("a & b = " + (a & b));     // 輸出a & b = 1
    System.out.println("a | b = " + (a | b));     // 輸出a | b = 15
    System.out.println("a ^ b = " + (a ^ b));     // 輸出a ^ b = 14
    System.out.println("~a = " + (~a));           // 輸出~a = -31
    System.out.println("a << 2 = " + (a << 2));   // 輸出a << 2 = 40
    System.out.println("a >> 2 = " + (a >> 2));   // 輸出a >> 2 = 2

    // 字符串格式化
    String name = "Tom";
    int age = 18;
    System.out.printf("My name is %s, I am %d years old.", name, age); // 輸出My name is Tom, I am 18 years old.

    // 字符串拆分
    String str = "a,b,c,d,e";
    String[] array = str.split(",");
    System.out.println(Arrays.toString(array)); // 輸出[a, b, c, d, e]

    // 字符串連接
    String str1 = "hello";
    String str2 = "world";
    String string = str1 + " " + str2;
    System.out.println(string); // 輸出hello world

    // 字符串替換
    String oldString = "hello world";
    String newString = oldString.replace("world", "Java");
    System.out.println(newString); // 輸出hello Java

    // 字符串大小寫轉(zhuǎn)換
    String s = "Hello World";
    String lowStr = s.toLowerCase();
    String upStr = s.toUpperCase();
    System.out.println(lowStr); // 輸出hello world
    System.out.println(upStr);  // 輸出HELLO WORLD
  }
}