STRINGS

Strings in Vint

Strings are a sequence of characters used to represent text in the Vint programming language. Here’s a detailed explanation of how to work with strings, including syntax, manipulation, and useful built-in methods.

Basic Syntax

In Vint, strings can be enclosed in either single quotes ('') or double quotes (""):

print("Hello")  // Output: Hello

let name = 'Tachera'

print("Hello", name)  // Output: Hello Tachera

Concatenating Strings

Strings can be concatenated using the + operator:

let greeting = "Hello" + " " + "World"
print(greeting)  // Output: Hello World

let message = "Hello"
message += " World"
// Output: Hello World

You can also repeat a string a specific number of times using the * operator:

print("Hello " * 3)  // Output: Hello Hello Hello

let repeated = "World"
repeated *= 2
// Output: WorldWorld

Looping Over a String

You can loop through each character of a string using the for keyword:

let name = "Avicenna"

for char in name {
    print(char)
}
// Output:
// A
// v
// i
// c
// e
// n
// n
// a

You can also loop through the string using its index and character:

for i, char in name {
    print(i, "=>", char)
}
// Output:
// 0 => A
// 1 => v
// 2 => i
// 3 => c
// 4 => e
// 5 => n
// 6 => n
// 7 => a

Comparing Strings

You can compare two strings using the == operator:

let a = "Vint"
print(a == "Vint")  // Output: true
print(a == "vint")  // Output: false

String Methods

Length of a String (length)

You can find the length of a string using the length method. It does not accept any parameters:

let message = "Vint"
print(message.length())  // Output: 4

Convert to Uppercase (upper)

This method converts the string to uppercase:

let text = "vint"
print(text.upper())  // Output: VINT

Convert to Lowercase (lower)

This method converts the string to lowercase:

let text = "VINT"
print(text.lower())  // Output: vint

Split a String (split)

The split method splits a string into an array based on a specified delimiter. If no delimiter is provided, it splits by whitespace.

Example without a delimiter:

let sentence = "Vint programming language"
let words = sentence.split()
print(words)  // Output: ["Vint", "programming", "language"]

Example with a delimiter:

let sentence = "Vint,programming,language"
let words = sentence.split(",")
print(words)  // Output: ["Vint", "programming", "language"]

Replace Substrings (replace)

You can replace a substring with another string using the replace method:

let greeting = "Hello World"
let newGreeting = greeting.replace("World", "Vint")
print(newGreeting)  // Output: Hello Vint

Trim Whitespace (trim)

You can remove whitespace from the start and end of a string using the trim method:

let text = "  Hello World  "
print(text.trim())  // Output: "Hello World"

Check String Start (startsWith)

The startsWith method checks if a string starts with a specified prefix:

let text = "Hello World"
print(text.startsWith("Hello"))  // Output: true
print(text.startsWith("World"))  // Output: false

Check String End (endsWith)

The endsWith method checks if a string ends with a specified suffix:

let text = "Hello World"
print(text.endsWith("World"))   // Output: true
print(text.endsWith("Hello"))   // Output: false

Check String Contains (includes)

The includes method checks if a string contains a specified substring:

let text = "Hello World"
print(text.includes("lo Wo"))   // Output: true
print(text.includes("xyz"))     // Output: false

Repeat String (repeat)

The repeat method repeats a string a specified number of times:

let text = "Ha"
print(text.repeat(3))  // Output: "HaHaHa"
print("X".repeat(5))   // Output: "XXXXX"

Capitalize String (capitalize)

The capitalize method capitalizes the first letter of a string:

let text = "hello world"
print(text.capitalize())  // Output: "Hello world"

Check if Numeric (isNumeric)

The isNumeric method checks if a string contains only numeric characters:

print("123".isNumeric())      // Output: true
print("12.34".isNumeric())    // Output: true
print("abc".isNumeric())      // Output: false
print("12a".isNumeric())      // Output: false

Check if Alphabetic (isAlpha)

The isAlpha method checks if a string contains only alphabetic characters:

print("hello".isAlpha())      // Output: true
print("Hello".isAlpha())      // Output: true
print("hello123".isAlpha())   // Output: false
print("hello world".isAlpha()) // Output: false (space is not alphabetic)

Case-Insensitive Compare (compareIgnoreCase)

The compareIgnoreCase method compares strings ignoring case differences:

let text = "Hello"
print(text.compareIgnoreCase("hello"))   // Output: 0 (equal)
print(text.compareIgnoreCase("apple"))   // Output: 1 (greater)
print(text.compareIgnoreCase("zebra"))   // Output: -1 (less)

Format String (format)

The format method applies simple formatting to strings using placeholders:

let template = "Hello {0}, you are {1} years old"
print(template.format("John", 25))  // Output: "Hello John, you are 25 years old"

let message = "The result is {0}"
print(message.format(42))  // Output: "The result is 42"

Remove Accents (removeAccents)

The removeAccents method removes accent characters from a string:

print("café".removeAccents())     // Output: "cafe"
print("naïve".removeAccents())    // Output: "naive"
print("résumé".removeAccents())   // Output: "resume"

Convert to Integer (toInt)

The toInt method converts a string to an integer:

print("123".toInt())    // Output: 123
print("-456".toInt())   // Output: -456
// Note: Returns an error if the string is not a valid integer

let message = "  Hello World  "
print(message.trim())  // Output: Hello World

Get a Substring (substring)

You can extract a substring from a string by specifying the starting and ending indices:

let sentence = "Vint programming"
print(sentence.substring(0, 4))  // Output: Vint

Find the Index of a Substring (indexOf)

You can find the index of a substring within a string using the indexOf method:

let sentence = "Vint programming"
print(sentence.indexOf("programming"))  // Output: 5

Slugify a String (slug)

You can convert a string into a URL-friendly format (slug) using the slug method:

let title = "Creating a Slug String"
print(title.slug())  // Output: creating-a-slug-string

Checking Substring Presence (contains)

Check if a string contains a specific substring:

let name = "Tachera Sasi"
print(name.contains("Sasi"))  // Output: true

Get Character at Index (charAt)

Get the character at a specific index:

let word = "Hello"
print(word.charAt(1))  // Output: e
print(word.charAt(10)) // Output: "" (empty string for out of bounds)

Repeat String (times)

Repeat a string a specified number of times:

let pattern = "Ha"
print(pattern.times(3))  // Output: HaHaHa

Pad String Start (padStart)

Pad the string to a target length from the beginning:

let num = "5"
print(num.padStart(3, "0"))  // Output: 005

let word = "hi"
print(word.padStart(5, "*"))  // Output: ***hi

Pad String End (padEnd)

Pad the string to a target length from the end:

let num = "5"
print(num.padEnd(3, "0"))  // Output: 500

let word = "hi"
print(word.padEnd(5, "*"))  // Output: hi***

Check String Start (startsWith)

Check if a string starts with a specified prefix:

let message = "Hello World"
print(message.startsWith("Hello"))  // Output: true
print(message.startsWith("World"))  // Output: false

Check String End (endsWith)

Check if a string ends with a specified suffix:

let filename = "document.pdf"
print(filename.endsWith(".pdf"))  // Output: true
print(filename.endsWith(".txt"))  // Output: false

Extract Slice (slice)

Extract a section of the string:

let text = "Hello World"
print(text.slice(0, 5))   // Output: Hello
print(text.slice(6))      // Output: World
print(text.slice(-5))     // Output: World

Example Usage

Here’s an example of how you might use these string operations in Vint:

import "string"

// Example: Trim whitespace
let trimmed = string.trim("  Hello, World!  ")
print(trimmed)  // Output: "Hello, World!"

// Example: Check if a string contains a substring
let containsResult = string.contains("Hello, World!", "World")
print(containsResult)  // Output: true

// Example: Convert to uppercase
let upperResult = string.toUpper("hello")
print(upperResult)  // Output: "HELLO"

// Example: Convert to lowercase
let lowerResult = string.toLower("HELLO")
print(lowerResult)  // Output: "hello"

// Example: Replace a substring
let replaceResult = string.replace("Hello, World!", "World", "Vint")
print(replaceResult)  // Output: "Hello, Vint!"

// Example: Split a string into parts
let splitResult = string.split("a,b,c,d", ",")
print(splitResult)  // Output: ["a", "b", "c", "d"]

// Example: Join string parts
let joinResult = string.join(["a", "b", "c"], "-")
print(joinResult)  // Output: "a-b-c"

// Example: Get the length of a string
let lengthResult = string.length("Hello")
print(lengthResult)  // Output: 5

Example with Vint Data

Here's an example using Vint-specific strings:

let name = "Tachera Sasi"
let reversed = name.reverse()
print(reversed)  // Output: "isaS arehcaT"

let upperName = name.upper()
print(upperName)  // Output: "TACHERA SASI"

let trimmedName = name.trim("T")
print(trimmedName)  // Output: "achera Sasi"

Understanding how to manipulate and work with strings in Vint allows you to efficiently handle text data in your programs.