Chuỗi ký tự (String) trong Kotlin

val name = "Kotlin"
val greeting: String = "Hello"
 
// Multi-line string
val multiLine = """
    Line 1
    Line 2
    Line 3
""".trimIndent()

val name = "Alice"
val age = 25
 
println("Name: $name")
println("Age: $age")
println("Next year: ${age + 1}")

val str = "Kotlin"
 
println(str[0])        // K
println(str.first())   // K
println(str.last())    // n
println(str.length)    // 6

val str = "  Kotlin Programming  "
 
// Case conversion
println(str.uppercase())       // "  KOTLIN PROGRAMMING  "
println(str.lowercase())       // "  kotlin programming  "
 
// Trim
println(str.trim())            // "Kotlin Programming"
println(str.trimStart())       // "Kotlin Programming  "
println(str.trimEnd())         // "  Kotlin Programming"
 
// Replace
println(str.replace("Kotlin", "Java"))
 
// Contains
println(str.contains("Kotlin"))  // true
 
// Split
val parts = "a,b,c".split(",")   // ["a", "b", "c"]

val builder = StringBuilder()
builder.append("Hello")
builder.append(" ")
builder.append("World")
println(builder.toString())  // "Hello World"

val str1 = "Kotlin"
val str2 = "Kotlin"
val str3 = "kotlin"
 
println(str1 == str2)                    // true
println(str1 == str3)                    // false
println(str1.equals(str3, ignoreCase = true))  // true

val str = "Kotlin"
 
println(str.substring(0, 3))     // "Kot"
println(str.substring(2))        // "tlin"
println(str.take(3))             // "Kot"
println(str.takeLast(3))         // "lin"
println(str.drop(2))             // "tlin"

val json = """
{
    "name": "Alice",
    "age": 25
}
"""
 
val regex = """\d+"""  // Không cần escape