How Strings Work Differently Across Languages in DSA Go - Code Step by Step

Practice - 5 Tasks

1fill in blank

easy

Complete the code to get the length of the string in Go.

DSA Go

str := "hello"
length := len([1])
fmt.Println(length)

Drag options to blanks, or click blank then click option'

Alen

B"str"

Cstring

Dstr

Attempts:

3 left

💡 Hint

Common Mistakes

Passing the string literal with quotes instead of the variable.

Using string or len as argument instead of the variable.

In Go, len() returns the number of bytes in the string. We pass the string variable str to get its length.

2fill in blank

medium

Complete the code to convert a string to a slice of runes for proper Unicode handling.

DSA Go

str := "hello"
runes := [][1](str)
fmt.Println(runes)

Drag options to blanks, or click blank then click option'

Abyte

Brune

Cint

Dstring

Attempts:

3 left

💡 Hint

Common Mistakes

Using byte which only handles raw bytes, not Unicode.

Using int or string which are incorrect types here.

In Go, converting a string to a slice of rune allows correct handling of Unicode characters, as rune represents a Unicode code point.

3fill in blank

hard

Fix the error in the code to correctly print each Unicode character in the string.

DSA Go

str := "héllo"
for _, [1] := range str {
    fmt.Printf("%c ", r)
}

Drag options to blanks, or click blank then click option'

Ar

Bchar

Ci

Dc

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different variable name than the one printed.

Confusing the index variable with the rune variable.

In a range loop over a string, the second variable holds the rune (Unicode character). The code prints r, so the variable must be named r.

4fill in blank

hard

Fill both blanks to correctly convert a string to a byte slice and back to string.

DSA Go

str := "hello"
bytes := [][1](str)
newStr := string([2])
fmt.Println(newStr)

Drag options to blanks, or click blank then click option'

Abyte

Brune

Cbytes

Dstr

Attempts:

3 left

💡 Hint

Common Mistakes

Using rune instead of byte for byte slice.

Using the original string variable instead of the byte slice for conversion.

To convert a string to bytes, use []byte. To convert bytes back to string, use string(bytes).

5fill in blank

hard

Fill all three blanks to create a map of characters to their counts from a string.

DSA Go

str := "hello"
counts := make(map[[1]]int)
for _, [2] := range str {
    counts[[3]]++
}
fmt.Println(counts)

Drag options to blanks, or click blank then click option'

Arune

Bchar

Cc

Dbyte

Attempts:

3 left

💡 Hint

Common Mistakes

Using byte as map key which may not handle Unicode correctly.

Using different variable names for loop variable and map key.

The map key type should be rune to handle Unicode characters. The loop variable is commonly c, which is used as the key to count characters.

Practice

1. In Go, what is the type of a string internally?
var s = "hello"

easy

A. A sequence of bytes representing UTF-8 encoded characters

B. An array of Unicode code points (runes)

C. A linked list of characters

D. A pointer to a null-terminated character array

Solution

1. Step 1: Understand Go string representation

   Go strings are immutable sequences of bytes, typically UTF-8 encoded.

2. Step 2: Compare with other languages

   Unlike some languages that use arrays of Unicode code points, Go uses bytes internally.

3. Final Answer:

   A sequence of bytes representing UTF-8 encoded characters -> Option A

4. Quick Check:

   Go strings = UTF-8 bytes [OK]

Hint: Remember Go strings are byte sequences, not rune arrays [OK]

Common Mistakes:

• Thinking Go strings store runes directly
• Assuming null-terminated strings like C
• Confusing with linked list or array types

2. Which of the following is the correct way to get the length of a string in Go?
s := "hello"

easy

A. length(s)

B. s.length()

C. len(s)

D. s.len

Solution

1. Step 1: Recall Go built-in function for length

   Go uses the built-in function len() to get the length of strings and slices.

2. Step 2: Check other options

   Methods like s.length() or s.len do not exist in Go; length(s) is not valid syntax.

3. Final Answer:

   len(s) -> Option C

4. Quick Check:

   Use len() for string length in Go [OK]

Hint: Use len() function to get string length in Go [OK]

Common Mistakes:

• Using method calls like s.length() from other languages
• Trying to access length as a property
• Using undefined functions like length()

3. What will be the output of this Go code?

package main
import "fmt"
func main() {
  s := "Go😊"
  fmt.Println(len(s))
}

medium

A. 3

B. 6

C. 4

D. 5

Solution

1. Step 1: Analyze string content and encoding

   The string "Go😊" has 'G' and 'o' as 1 byte each, and the emoji '😊' is a 4-byte UTF-8 character.

2. Step 2: Calculate total byte length

   Total bytes = 1 (G) + 1 (o) + 4 (😊) = 6 bytes.

3. Step 3: Check len() output

   len(s) returns the number of bytes, so output is 6.

4. Final Answer:

   6 -> Option B

5. Quick Check:

   len() counts bytes, not characters [OK]

Hint: len() returns bytes count, not character count [OK]

Common Mistakes:

• Assuming len() returns number of characters
• Ignoring multi-byte UTF-8 characters
• Confusing bytes with runes

4. Identify the error in this Go code that tries to print each character of a string:

package main
import "fmt"
func main() {
  s := "Go"
  for i := 0; i < len(s); i++ {
    fmt.Println(s[i])
  }
}

medium

A. It prints byte values, not characters

B. Syntax error in for loop

C. s[i] is invalid syntax

D. Missing import for fmt

Solution

1. Step 1: Understand s[i] in Go strings

   Accessing s[i] returns the byte at index i, not a character or string.

2. Step 2: Check output of fmt.Println(s[i])

   It prints the numeric byte value (ASCII code), not the character itself.

3. Final Answer:

   It prints byte values, not characters -> Option A

4. Quick Check:

   s[i] = byte, prints number [OK]

Hint: s[i] gives byte, convert to rune or string to print char [OK]

Common Mistakes:

• Expecting s[i] to print characters directly
• Ignoring byte vs rune difference
• Assuming syntax error where none exists

5. How can you correctly iterate over each Unicode character in a Go string to print them?
Choose the correct code snippet.

hard

A. for i := 0; i < len(s); i++ { fmt.Println(string(s[i])) }

B. for i := range s { fmt.Println(s[i]) }

C. for i, c := range s { fmt.Println(s[i]) }

D. for _, r := range s { fmt.Println(string(r)) }

Solution

1. Step 1: Understand iteration over strings in Go

   Using 'for _, r := range s' iterates over runes (Unicode code points), not bytes.

2. Step 2: Check printing each character

   Converting rune 'r' to string prints the actual character correctly.

3. Step 3: Analyze other options

   for i := 0; i < len(s); i++ { fmt.Println(string(s[i])) } prints bytes as strings, which may break multi-byte chars; C and D print bytes, not runes.

4. Final Answer:

   for _, r := range s { fmt.Println(string(r)) } -> Option D

5. Quick Check:

   Use range to get runes for correct Unicode iteration [OK]

Hint: Use 'for _, r := range s' to iterate Unicode chars [OK]

Common Mistakes:

• Iterating by byte index instead of runes
• Printing bytes as characters causing errors
• Confusing index and rune variables