从给定的字符串中删除空格

给定一个字符串，从字符串中删除所有空格并返回它。

Input:  "g  eeks   for ge  eeks  "
Output: "geeksforgeeks"

预期的时间复杂度为 O(n) 并且仅遍历一次字符串。

我们强烈建议您单击此处并进行练习，然后再继续使用解决方案。

下面是一个简单的解决方案

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.

上述解决方案的时间复杂度为 O(n ² )。
更好的解决方案可以在 O(n) 时间内解决。这个想法是跟踪到目前为止看到的非空格字符的计数。

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'

下面是上述算法的实现。

C++

// An efficient C++ program to remove all spaces
// from a string
#include 
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

---

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

Javascript

 
      // An efficient JavaScript program to remove all
      // spaces from a string
       
      // Function to remove all spaces
      // from a given string
      function removeSpaces(str) {
        // To keep track of non-space
        // character count
        var count = 0;
 
        // Traverse the given string. If current
        // character is not space, then place
        // it at index 'count++'
        for (var i = 0; i < str.length; i++)
          if (str[i] !== " ") str[count++] = str[i];
         // here count is
        // incremented
 
        return count;
      }
 
      // Driver code
      var str = "g eeks for ge eeks ".split("");
      var i = removeSpaces(str);
      document.write(str.join("").substring(0, i));
       

输出

geeksforgeeeks

上述解决方案的时间复杂度是 O(n) 并且它只对字符串进行一次遍历。
Divyam Madaan 建议的另一个解决方案是使用预定义函数。这是实现：


C++

// CPP program to Remove spaces
// from a given string
 
#include 
#include 
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

Javascript

// javascript program to remove
// all spaces from a string
    // Function to remove all
    // spaces from a given string
     function removeSpace( str)
     {
        str = str.replace(/\s/g,'')
        return str;
    }
 
    // Driver Code   
        var str = "g eeks for ge eeks ";
        document.write(removeSpace(str));
 
// This code contributed by aashish1995

输出

geeksforgeeeks

另一种使用预定义 STL 函数（如count() 、 remove() 、 getline()和resize() ）解决此问题的方法也存在。这是相同的实现：

C++

#include 
using namespace std;
int main()
{
    string s = "g e e k s f o r g e e k s";
 
    cout << "string with spaces is " << s << endl;
 
    int l = s.length(); // storing the length of the string
 
    int c
        = count(s.begin(), s.end(),
                ' '); // counting the number of whitespaces
 
    remove(s.begin(), s.end(),
           ' '); // removing all the whitespaces
 
    s.resize(l - c); // resizing the string to l-c
 
    cout << "string without spaces is " << s << endl;
 
    return 0;
}

输出

string with spaces is g e e k s f o r g e e k s
string without spaces is geeksforgeeks