Remove spaces from a given string (original) (raw)
Last Updated : 11 Apr, 2026
Given a string **s, remove all spaces from the string and return it.
**Examples:
**Input: s = "g eeks for ge eeks "
**Output: geeksforgeeks
**Explanation: All the spaces have been removed.**Input: s = " abc d "
**Output: abcd
**Explanation: All the spaces including the leading ones have been removed.
Table of Content
- [Naive Approach] Using Brute Force - O(n*n) Time and O(1) Space
- [Expected Approach] Using Two Pointer - O(n) Time and O(1) Space
- Using Built-in functions - O(n) Time and O(1) Space
[Naive Approach] Using Brute Force - O(n*n) Time and O(1) Space
Traverse the string and whenever a space is found, shift all the following characters one position to the left and reduce the effective length of the string.
Dry run for s = " gf g":
- Initialize n = 5 (length of the string).
- For i = 0, ' ' is space then shift all characters left so, string becomes "gf g" and reduce n to 4, decrement i.
- For i = 0, 'g' is not space then move to next index.
- For i = 1, 'f' is not space then move to next index.
- For i = 2, ' ' is space then shift all characters left so, string becomes "gfg" and reduce n to 3, decrement i.
- For i = 2, 'g' is not space then move to next index.
- Traversal complete, return substring s[0 to n-1]. C++ `
#include #include using namespace std;
string removeSpaces(string& s) { int n = s.length();
for (int i = 0; i < n; i++) {
if (s[i] == ' ') {
// shift all characters to the left
// starting from current index
for (int j = i; j < n - 1; j++) {
s[j] = s[j + 1];
}
n--;
i--;
}
}
// return string up to new valid length
// without spaces
return s.substr(0, n);}
int main() { string s = "g eeks for ge eeks "; cout << removeSpaces(s); return 0; }
C
#include <stdio.h> #include <string.h>
char* removeSpaces(char s[]) { int n = strlen(s);
for (int i = 0; i < n; i++) {
if (s[i] == ' ') {
// shift all characters to the left
// starting from current index
for (int j = i; j < n - 1; j++) {
s[j] = s[j + 1];
}
n--;
i--;
}
}
// return string up to new valid length
// without spaces
s[n] = '\0';
return s;}
int main() { char s[] = "g eeks for ge eeks "; printf("%s", removeSpaces(s)); return 0; }
Java
class GfG {
static String removeSpaces(String s) {
char[] arr = s.toCharArray();
int n = arr.length;
for (int i = 0; i < n; i++) {
if (arr[i] == ' ') {
// shift all characters to the left
// starting from current index
for (int j = i; j < n - 1; j++) {
arr[j] = arr[j + 1];
}
n--;
i--;
}
}
// return string up to new valid length
// without spaces
return new String(arr, 0, n);
}
public static void main(String[] args) {
String s = "g eeks for ge eeks ";
System.out.print(removeSpaces(s));
}}
Python
def removeSpaces(s):
# convert to list
# (strings are immutable in Python)
s = list(s)
n = len(s)
i = 0
while i < n:
if s[i] == ' ':
# shift all characters to the left
# starting from current index
for j in range(i, n - 1):
s[j] = s[j + 1]
n -= 1
i -= 1
i += 1
# return string up to new valid length
# without spaces
return "".join(s[:n])if name == "main": s = "g eeks for ge eeks " print(removeSpaces(s))
C#
using System;
class GfG {
static string removeSpaces(string s) {
char[] arr = s.ToCharArray();
int n = arr.Length;
for (int i = 0; i < n; i++) {
if (arr[i] == ' ') {
// shift all characters to the left
// starting from current index
for (int j = i; j < n - 1; j++) {
arr[j] = arr[j + 1];
}
n--;
i--;
}
}
// return string up to new valid length
// without spaces
return new string(arr, 0, n);
}
static void Main() {
string s = "g eeks for ge eeks ";
Console.Write(removeSpaces(s));
}}
JavaScript
function removeSpaces(s) { s = s.split(''); let n = s.length;
for (let i = 0; i < n; i++) {
if (s[i] === ' ') {
// shift all characters to the left
// starting from current index
for (let j = i; j < n - 1; j++) {
s[j] = s[j + 1];
}
n--;
i--;
}
}
// return string up to new valid length
// without spaces
return s.slice(0, n).join("");}
// Driver code let s = "g eeks for ge eeks "; console.log(removeSpaces(s));
`
[Expected Approach] Using Two Pointer - O(n) Time and O(1) Space
Traverse the string using two indices, where one index reads each character and the other writes only non-space characters. Whenever a non-space character is found, place it at the write index and move both pointers accordingly. This way, all non-space characters are shifted forward without using extra space.
Dry run for s = "gf g":
- Initialize two pointers i = 0, itr = 0
- For i = 0, 'g' is not space then copy to s[itr], increment itr to 1
- For i = 1, 'f' is not space then copy to s[1], itr to 2
- For i = 2, ' ' is space then skip, only i moves
- For i = 3, ' ' is space then skip
- For i = 4, 'g' is not space then copy to s[2], itr to 3
- Traversal complete, return substring s[0 to itr-1] C++ `
#include #include using namespace std;
string removeSpaces(string& s) { int n = s.length(); int i = 0, itr = 0;
// Iterate through the string
while (i < n) {
// Check if current character
// is not a space
if (s[i] != ' '){
// Copy the non-space character
// to the new string
s[itr++] = s[i];
}
i++;
}
// Return only the modified part of the string
// without any extra characters
return s.substr(0, itr);}
int main() { string s = "g eeks for ge eeks "; cout << removeSpaces(s); return 0; }
C
#include <stdio.h> #include <string.h>
char* removeSpaces(char s[]) { int n = strlen(s); int i = 0, itr = 0;
// Iterate through the string
while (i < n) {
// Check if current character
// is not a space
if (s[i] != ' ') {
// Copy the non-space character
// to the new string
s[itr++] = s[i];
}
i++;
}
// add null character to mark end of string
s[itr] = '\0';
// Return only the modified part of the string
// without any extra characters
return s;}
int main() { char s[] = "g eeks for ge eeks "; printf("%s", removeSpaces(s)); return 0; }
Java
class GfG {
static String removeSpaces(String s) {
int n = s.length();
int i = 0, itr = 0;
// convert string to character array
char[] arr = s.toCharArray();
// Iterate through the string
while (i < n) {
// Check if current character
// is not a space
if (arr[i] != ' ') {
// Copy the non-space character
// to the new string
arr[itr++] = arr[i];
}
i++;
}
// Return only the modified part of the string
// without any extra characters
return new String(arr, 0, itr);
}
public static void main(String[] args) {
String s = "g eeks for ge eeks ";
System.out.print(removeSpaces(s));
}}
Python
def removeSpaces(s): n = len(s) i = 0 itr = 0
# convert to list
# (strings are immutable in Python)
s = list(s)
# Iterate through the string
while i < n:
# Check if current character
# is not a space
if s[i] != ' ':
# Copy the non-space character
# to the new string
s[itr] = s[i]
itr += 1
i += 1
# Return only the modified part of the string
# without any extra characters
return "".join(s[:itr])if name == "main": s = "g eeks for ge eeks " print(removeSpaces(s))
C#
using System;
class GfG {
static string removeSpaces(string s) {
int n = s.Length;
int i = 0, itr = 0;
// convert string to character array
char[] arr = s.ToCharArray();
// Iterate through the string
while (i < n) {
// Check if current character
// is not a space
if (arr[i] != ' ') {
// Copy the non-space character
// to the new string
arr[itr++] = arr[i];
}
i++;
}
// Return only the modified part of the string
// without any extra characters
return new string(arr, 0, itr);
}
static void Main() {
string s = "g eeks for ge eeks ";
Console.Write(removeSpaces(s));
}}
JavaScript
function removeSpaces(s) { let n = s.length; let i = 0, itr = 0;
// convert string to character array
let arr = s.split('');
// Iterate through the string
while (i < n) {
// Check if current character
// is not a space
if (arr[i] !== ' ') {
// Copy the non-space character
// to the new string
arr[itr++] = arr[i];
}
i++;
}
// Return only the modified part of the string
// without any extra characters
return arr.slice(0, itr).join("");}
// Driver code let s = "g eeks for ge eeks "; console.log(removeSpaces(s));
`
Using Built-in functions - O(n) Time and O(1) Space
Use a built-in string function to remove or skip all space characters while forming the result. This processes each character once and returns a new string without spaces in linear time.
C++ `
#include #include using namespace std;
string removeSpaces(string& s) {
// move non-space characters to front
auto new_end = remove(s.begin(), s.end(), ' ');
// erase extra part
s.erase(new_end, s.end());
return s;}
int main() { string s = "g eeks for ge eeks "; cout << removeSpaces(s); return 0; }
Java
public class GfG {
static String removeSpaces(String s) {
// replace all spaces with empty string
s = s.replace(" ", "");
return s;
}
public static void main(String[] args) {
String s = "g eeks for ge eeks ";
System.out.print(removeSpaces(s));
}}
Python
def removeSpaces(s):
s = s.replace(" ", "")
return sif name == "main": s = "g eeks for ge eeks " print(removeSpaces(s), end="")
C#
using System;
class GfG {
static string RemoveSpaces(string s) {
// replace all spaces with empty string
s = s.Replace(" ", "");
return s;
}
static void Main() {
string s = "g eeks for ge eeks ";
Console.Write(RemoveSpaces(s));
}}
JavaScript
function removeSpaces(s) {
// replace all spaces with empty string
return s.replace(/ /g, "");}
// Driver code let s = "g eeks for ge eeks "; console.log(removeSpaces(s));
`
**Note: C does not have a built-in function to remove spaces, so it must be done manually.