Revision of Working with Strings

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## Working with Strings

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In both python and Java, samples of working with common string operations: split,

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capitalization, concatenation, replacing characters, working with sentences.

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Key differences:

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- Python: Has built-in title(), capitalize() methods; f-strings for formatting

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- Java: More verbose; often requires manual implementation or StringBuilder

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- Python: Strings are immutable but syntax is cleaner

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- Java: Strings are also immutable; use StringBuilder for efficiency with multiple operations

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### in Python

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```python

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# Split operations

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text = "hello world python"

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words = text.split() # ['hello', 'world', 'python']

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csv = "apple,banana,orange"

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fruits = csv.split(',') # ['apple', 'banana', 'orange']

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# Capitalization

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name = "john doe"

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print(name.capitalize()) # "John doe"

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print(name.title()) # "John Doe"

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print(name.upper()) # "JOHN DOE"

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print(name.lower()) # "john doe"

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# Concatenation

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# Method 1: + operator

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greeting = "Hello" + " " + "World" # "Hello World"

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# Method 2: join() - more efficient for multiple strings

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words = ["Python", "is", "awesome"]

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sentence = " ".join(words) # "Python is awesome"

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# Method 3: f-strings (Python 3.6+)

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name = "Alice"

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age = 25

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message = f"{name} is {age} years old" # "Alice is 25 years old"

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# Replacing characters/substrings

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text = "Hello World"

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new_text = text.replace("World", "Python") # "Hello Python"

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phone = "123-456-7890"

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clean = phone.replace("-", "") # "1234567890"

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# Working with sentences

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sentence = "this is a sentence. and another one."

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# Capitalize first letter of each sentence

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sentences = sentence.split('. ')

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capitalized = '. '.join(s.capitalize() for s in sentences)

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# Result: "This is a sentence. And another one."

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# Strip whitespace

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messy = " hello world \n"

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clean = messy.strip() # "hello world"

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# Check string properties

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text = "Hello123"

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print(text.isalnum()) # True

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print(text.isalpha()) # False

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print(text.startswith("Hello")) # True

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print(text.endswith("123")) # True

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```

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### in Java

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```java

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// Split operations

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String text = "hello world java";

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String[] words = text.split(" "); // ["hello", "world", "java"]

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String csv = "apple,banana,orange";

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String[] fruits = csv.split(","); // ["apple", "banana", "orange"]

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// Capitalization

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String name = "john doe";

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// Capitalize first letter only

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String capitalized = name.substring(0, 1).toUpperCase() + name.substring(1);

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// Result: "John doe"

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// Title case (manual - Java doesn't have built-in)

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String[] words = name.split(" ");

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StringBuilder titleCase = new StringBuilder();

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for (String word : words) {

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titleCase.append(word.substring(0, 1).toUpperCase())

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.append(word.substring(1).toLowerCase())

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.append(" ");

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}

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String title = titleCase.toString().trim(); // "John Doe"

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// Upper and lower case

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String upper = name.toUpperCase(); // "JOHN DOE"

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String lower = name.toLowerCase(); // "john doe"

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// Concatenation

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// Method 1: + operator (creates new strings)

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String greeting = "Hello" + " " + "World"; // "Hello World"

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// Method 2: StringBuilder (efficient for multiple operations)

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StringBuilder sb = new StringBuilder();

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sb.append("Java").append(" is ").append("awesome");

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String sentence = sb.toString(); // "Java is awesome"

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// Method 3: String.join()

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String[] words = {"Java", "is", "awesome"};

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String joined = String.join(" ", words); // "Java is awesome"

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// Method 4: String.format()

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String name = "Alice";

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int age = 25;

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String message = String.format("%s is %d years old", name, age);

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// Result: "Alice is 25 years old"

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// Replacing characters/substrings

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String text = "Hello World";

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String newText = text.replace("World", "Java"); // "Hello Java"

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String phone = "123-456-7890";

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String clean = phone.replace("-", ""); // "1234567890"

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// Replace first occurrence only

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String repeated = "abc abc abc";

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String replaced = repeated.replaceFirst("abc", "xyz"); // "xyz abc abc"

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// Working with sentences

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String sentence = "this is a sentence. and another one.";

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// Capitalize sentences (manual approach)

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String[] sentences = sentence.split("\\. ");

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StringBuilder result = new StringBuilder();

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for (String s : sentences) {

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if (!s.isEmpty()) {

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result.append(Character.toUpperCase(s.charAt(0)))

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.append(s.substring(1))

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.append(". ");

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}

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}

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String capitalized = result.toString().trim();

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// Result: "This is a sentence. And another one."

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// Trim whitespace

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String messy = " hello world \n";

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String clean = messy.trim(); // "hello world"

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// Check string properties

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String text = "Hello123";

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System.out.println(text.matches("[a-zA-Z0-9]+")); // true (alphanumeric)

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System.out.println(text.matches("[a-zA-Z]+")); // false (not just letters)

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System.out.println(text.startsWith("Hello")); // true

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System.out.println(text.endsWith("123")); // true

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```

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kristofer / Working with Strings

kristofer revised this gist 1763751698. Go to revision

kristofer revised this gist 1763751642. Go to revision

		@@ -0,0 +1,154 @@
1	+	## Working with Strings
2	+
3	+	In both python and Java, samples of working with common string operations: split,
4	+	capitalization, concatenation, replacing characters, working with sentences.
5	+
6	+	Key differences:
7	+
8	+	- Python: Has built-in title(), capitalize() methods; f-strings for formatting
9	+	- Java: More verbose; often requires manual implementation or StringBuilder
10	+	- Python: Strings are immutable but syntax is cleaner
11	+	- Java: Strings are also immutable; use StringBuilder for efficiency with multiple operations
12	+
13	+	### in Python
14	+
15	+	```python
16	+	# Split operations
17	+	text = "hello world python"
18	+	words = text.split() # ['hello', 'world', 'python']
19	+	csv = "apple,banana,orange"
20	+	fruits = csv.split(',') # ['apple', 'banana', 'orange']
21	+
22	+	# Capitalization
23	+	name = "john doe"
24	+	print(name.capitalize()) # "John doe"
25	+	print(name.title()) # "John Doe"
26	+	print(name.upper()) # "JOHN DOE"
27	+	print(name.lower()) # "john doe"
28	+
29	+	# Concatenation
30	+	# Method 1: + operator
31	+	greeting = "Hello" + " " + "World" # "Hello World"
32	+
33	+	# Method 2: join() - more efficient for multiple strings
34	+	words = ["Python", "is", "awesome"]
35	+	sentence = " ".join(words) # "Python is awesome"
36	+
37	+	# Method 3: f-strings (Python 3.6+)
38	+	name = "Alice"
39	+	age = 25
40	+	message = f"{name} is {age} years old" # "Alice is 25 years old"
41	+
42	+	# Replacing characters/substrings
43	+	text = "Hello World"
44	+	new_text = text.replace("World", "Python") # "Hello Python"
45	+	phone = "123-456-7890"
46	+	clean = phone.replace("-", "") # "1234567890"
47	+
48	+	# Working with sentences
49	+	sentence = "this is a sentence. and another one."
50	+	# Capitalize first letter of each sentence
51	+	sentences = sentence.split('. ')
52	+	capitalized = '. '.join(s.capitalize() for s in sentences)
53	+	# Result: "This is a sentence. And another one."
54	+
55	+	# Strip whitespace
56	+	messy = " hello world \n"
57	+	clean = messy.strip() # "hello world"
58	+
59	+	# Check string properties
60	+	text = "Hello123"
61	+	print(text.isalnum()) # True
62	+	print(text.isalpha()) # False
63	+	print(text.startswith("Hello")) # True
64	+	print(text.endswith("123")) # True
65	+
66	+	```
67	+
68	+
69	+	### in Java
70	+
71	+	```java
72	+	// Split operations
73	+	String text = "hello world java";
74	+	String[] words = text.split(" "); // ["hello", "world", "java"]
75	+	String csv = "apple,banana,orange";
76	+	String[] fruits = csv.split(","); // ["apple", "banana", "orange"]
77	+
78	+	// Capitalization
79	+	String name = "john doe";
80	+	// Capitalize first letter only
81	+	String capitalized = name.substring(0, 1).toUpperCase() + name.substring(1);
82	+	// Result: "John doe"
83	+
84	+	// Title case (manual - Java doesn't have built-in)
85	+	String[] words = name.split(" ");
86	+	StringBuilder titleCase = new StringBuilder();
87	+	for (String word : words) {
88	+	titleCase.append(word.substring(0, 1).toUpperCase())
89	+	.append(word.substring(1).toLowerCase())
90	+	.append(" ");
91	+	}
92	+	String title = titleCase.toString().trim(); // "John Doe"
93	+
94	+	// Upper and lower case
95	+	String upper = name.toUpperCase(); // "JOHN DOE"
96	+	String lower = name.toLowerCase(); // "john doe"
97	+
98	+	// Concatenation
99	+	// Method 1: + operator (creates new strings)
100	+	String greeting = "Hello" + " " + "World"; // "Hello World"
101	+
102	+	// Method 2: StringBuilder (efficient for multiple operations)
103	+	StringBuilder sb = new StringBuilder();
104	+	sb.append("Java").append(" is ").append("awesome");
105	+	String sentence = sb.toString(); // "Java is awesome"
106	+
107	+	// Method 3: String.join()
108	+	String[] words = {"Java", "is", "awesome"};
109	+	String joined = String.join(" ", words); // "Java is awesome"
110	+
111	+	// Method 4: String.format()
112	+	String name = "Alice";
113	+	int age = 25;
114	+	String message = String.format("%s is %d years old", name, age);
115	+	// Result: "Alice is 25 years old"
116	+
117	+	// Replacing characters/substrings
118	+	String text = "Hello World";
119	+	String newText = text.replace("World", "Java"); // "Hello Java"
120	+	String phone = "123-456-7890";
121	+	String clean = phone.replace("-", ""); // "1234567890"
122	+
123	+	// Replace first occurrence only
124	+	String repeated = "abc abc abc";
125	+	String replaced = repeated.replaceFirst("abc", "xyz"); // "xyz abc abc"
126	+
127	+	// Working with sentences
128	+	String sentence = "this is a sentence. and another one.";
129	+	// Capitalize sentences (manual approach)
130	+	String[] sentences = sentence.split("\\. ");
131	+	StringBuilder result = new StringBuilder();
132	+	for (String s : sentences) {
133	+	if (!s.isEmpty()) {
134	+	result.append(Character.toUpperCase(s.charAt(0)))
135	+	.append(s.substring(1))
136	+	.append(". ");
137	+	}
138	+	}
139	+	String capitalized = result.toString().trim();
140	+	// Result: "This is a sentence. And another one."
141	+
142	+	// Trim whitespace
143	+	String messy = " hello world \n";
144	+	String clean = messy.trim(); // "hello world"
145	+
146	+	// Check string properties
147	+	String text = "Hello123";
148	+	System.out.println(text.matches("[a-zA-Z0-9]+")); // true (alphanumeric)
149	+	System.out.println(text.matches("[a-zA-Z]+")); // false (not just letters)
150	+	System.out.println(text.startsWith("Hello")); // true
151	+	System.out.println(text.endsWith("123")); // true
152	+
153	+	```
154	+