Remove spaces from a given string
Given a string, remove all spaces from the string and return it.
Input: "g eeks for ge eeks " Output: "geeksforgeeks"
Expected time complexity is O(n) and only one traversal of string.
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Below is a Simple Solution
1) Iterate through all characters of given string, do following
a) If current character is a space, then move all subsequent
characters one position back and decrease length of the
result string.
Time complexity of above solution is O(n2).
A Better Solution can solve it in O(n) time. The idea is to keep track of count of non-space character seen so far.
1) Initialize 'count' = 0 (Count of non-space character seen so far)
2) Iterate through all characters of given string, do following
a) If current character is non-space, then put this character
at index 'count' and increment 'count'
3) Finally, put '\0' at index 'count'
Below is the implementation of above algorithm.
C++
// An efficient C++ program to remove all spaces // from a string #include <iostream> using namespace std; // Function to remove all spaces from a given string void removeSpaces(char *str) { // To keep track of non-space character count int count = 0; // Traverse the given string. If current character // is not space, then place it at index 'count++' for (int i = 0; str[i]; i++) if (str[i] != ' ') str[count++] = str[i]; // here count is // incremented str[count] = '\0'; } // Driver program to test above function int main() { char str[] = "g eeks for ge eeks "; removeSpaces(str); cout << str; return 0; } |
Java
// An efficient Java program to remove all spaces // from a string class GFG { // Function to remove all spaces // from a given string static int removeSpaces(char []str) { // To keep track of non-space character count int count = 0; // Traverse the given string. // If current character // is not space, then place // it at index 'count++' for (int i = 0; i<str.length; i++) if (str[i] != ' ') str[count++] = str[i]; // here count is // incremented return count; } // Driver code public static void main(String[] args) { char str[] = "g eeks for ge eeks ".toCharArray(); int i = removeSpaces(str); System.out.println(String.valueOf(str).subSequence(0, i)); } } // This code is contributed by Rajput-Ji |
Python
# Python program to Remove spaces from a given string # Function to remove all spaces from a given string def removeSpaces(string): # To keep track of non-space character count count = 0 list = [] # Traverse the given string. If current character # is not space, then place it at index 'count++' for i in xrange(len(string)): if string[i] != ' ': list.append(string[i]) return toString(list) # Utility Function def toString(List): return ''.join(List) # Driver program string = "g eeks for ge eeks "print removeSpaces(string) # This code is contributed by Bhavya Jain |
C#
// An efficient C# program to remove all // spaces from a string using System; class GFG { // Function to remove all spaces // from a given string static int removeSpaces(char []str) { // To keep track of non-space // character count int count = 0; // Traverse the given string. If current // character is not space, then place // it at index 'count++' for (int i = 0; i < str.Length; i++) if (str[i] != ' ') str[count++] = str[i]; // here count is // incremented return count; } // Driver code public static void Main(String[] args) { char []str = "g eeks for ge eeks ".ToCharArray(); int i = removeSpaces(str); Console.WriteLine(String.Join("", str).Substring(0, i)); } } // This code is contributed by 29AjayKumar |
Output:
geeksforgeeeks
Time complexity of above solution is O(n) and it does only one traversal of string.
Another solution suggested by Divyam Madaan is to use predefined functions. Here is the implementation:
C/C++
// CPP program to Remove spaces // from a given string #include <iostream> #include <algorithm> using namespace std; // Function to remove all spaces from a given string string removeSpaces(string str) { str.erase(remove(str.begin(), str.end(), ' '), str.end()); return str; } // Driver program to test above function int main() { string str = "g eeks for ge eeks "; str = removeSpaces(str); cout << str; return 0; } // This code is contributed by Divyam Madaan |
Java
// Java program to remove // all spaces from a string class GFG { // Function to remove all // spaces from a given string static String removeSpace(String str) { str = str.replaceAll("\\s",""); return str; } // Driver Code public static void main(String args[]) { String str = "g eeks for ge eeks "; System.out.println(removeSpace(str)); } } // This code is contributed by Kanhaiya. |
Python
# Python program to Remove spaces from a given string # Function to remove all spaces from a given string def removeSpaces(string): string = string.replace(' ','') return string # Driver program string = "g eeks for ge eeks "print(removeSpaces(string)) # This code is contributed by Divyam Madaan |
C#
// C# program to remove // all spaces from a string using System; class GFG { // Function to remove all // spaces from a given string static String removeSpace(String str) { str = str.Replace(" ",""); return str; } // Driver Code public static void Main() { String str = "g eeks for ge eeks "; Console.WriteLine(removeSpace(str)); } } // This code is contributed by // PrinciRaj1992 |
Output:
geeksforgeeeks
Thanks to Souravi Sarkar for suggesting this problem and initial solution.
Java | Removing whitespaces using Regex
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