🔤 String Manipulation¶

Prerequisites: None

Strings are sequences of characters. From simple name printing to complex text processing, mastering strings is vital. These problems will help you understand ASCII values, character arrays, and built-in string methods.

1. String Length¶

Rating: Beginner | Difficulty: Easy Input a string and find its length (without using built-in functions like strlen() or .length()).

💡 Hint

Loop until you hit the null terminator \0 (in C) or until the end of the character array.

2. Concatenate Two Strings¶

Rating: Beginner | Difficulty: Easy Join two strings together to form a single string.

💡 Hint

Create a larger array and copy characters from the first string, then the second.

3. String Reversal¶

Rating: Beginner | Difficulty: Easy Print a string in reverse order.

💡 Hint

Loop from length - 1 down to 0.

4. Check Palindrome String¶

Rating: Beginner | Difficulty: Easy Check if a string is a palindrome (e.g., "madam", "racecar").

💡 Hint

Compare characters from the start and end moving inwards.

5. Count Vowels and Consonants¶

Rating: Beginner | Difficulty: Easy Count how many vowels and consonants are in a given string.

💡 Hint

Use if to check if a character is in a, e, i, o, u.

6. Toggle Case¶

Rating: Intermediate | Difficulty: Medium Convert all lowercase characters to uppercase and vice versa in a string.

💡 Hint

Lowercase 'a' is 97 and Uppercase 'A' is 65. The difference is 32.

7. String Comparison¶

Rating: Beginner | Difficulty: Easy Compare two strings to see if they are identical (without using strcmp() or .equals()).

💡 Hint

Check if lengths match first, then compare character by character.

8. Remove All Spaces¶

Rating: Intermediate | Difficulty: Medium Input a sentence and remove all blank spaces from it.

💡 Hint

Copy only non-space characters into a new string.

9. Word Count¶

Rating: Intermediate | Difficulty: Medium Count the total number of words in a sentence.

💡 Hint

Count the number of spaces and add 1 (assuming single spaces between words).

10. Character Frequency¶

Rating: Advanced | Difficulty: Hard Find the frequency of a specific character in a string.

💡 Hint

Loop through the string and increment a counter whenever str[i] == ch.

11. Find Substring¶

Rating: Advanced | Difficulty: Hard Check if a specific word (substring) exists within a larger sentence.

💡 Hint

Use a nested loop to compare the pattern with sections of the main string.

12. Replace Character¶

Rating: Intermediate | Difficulty: Medium Replace every occurrence of a specific character with another (e.g., replace 'a' with '@').

💡 Hint

`if (str[i] == target) str[i] = replacement;`

13. Anagram Check¶

Rating: Advanced | Difficulty: Hard Check if two strings are anagrams (contain the same characters in any order, e.g., "listen" and "silent").

💡 Hint

Sort both strings and then compare them.

14. First Non-Repeating Character¶

Rating: Pro | Difficulty: Medium Find the first character in a string that does not repeat.

💡 Hint

Use a frequency array (size 256 for ASCII) to count occurrences first.

15. Title Case Conversion¶

Rating: Intermediate | Difficulty: Medium Convert a sentence to Title Case (capitalize the first letter of every word).

💡 Hint

Capitalize str[0] and any character that follows a space.

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