Replace all spaces in a string with “%20″

Problem: Write a C program that will replace all spaces with ‘%20′

Solution:
The algorithm is as follows:
1. Count the number of spaces during the first scan of the string.
2. Parse the string again from the end and for each character:

If a space is encountered, store “%20”.
Else, store the character as it is in the newly shifted location.

public static void ReplaceFun(char[] str, int length) {
	int spaceCount = 0, newLength, i = 0;
		
	for (i = 0; i < length; i++) 
	{
		if (str[i] == ‘ ‘) 
		{
			spaceCount++;
		}
	}
		
	newLength = length + spaceCount * 2;
	str[newLength] = ‘\0’;
	for (i = length - 1; i >= 0; i--)
	{
		if (str[i] == ‘ ‘)
		{
			str[newLength - 1] = ‘0’;
			str[newLength - 2] = ‘2’;
			str[newLength - 3] = ‘%’;		
			newLength = newLength - 3;
			
		} 
		else 
		{
			str[newLength - 1] = str[i];		
			newLength = newLength - 1;
		}
	}
}

Time Complexity: O(N), N is length of the string.

0 Thoughts on “Replace all spaces in a string with “%20″

  1. /*We can do this way too*/

    class ReplaceAllSpacesWithSpecifiedString
    {

    public static void main(String[] args)
    {
    System.out.println(replaceAllSpacesWithSpecifiedString(“aa bb ccc dddd ee ff ggg “, “%20″));
    }

    public static String replaceAllSpacesWithSpecifiedString(String str, String replace)
    {
    StringBuilder sb = new StringBuilder();
    int count = 0;

    for(int i = 0; i < str.length(); i++)
    {
    if(str.charAt(i) != ' ')
    count++;
    }

    for(int i = 0; ; i++)
    {
    if(str.charAt(i) != ' ')
    {
    sb.append(str.charAt(i));
    count–;
    }
    else
    sb.append("%20");
    if (count == 0)
    break;
    }
    return sb.toString();
    }

  2. Ashish Singh on November 22, 2014 at 1:01 pm said:

    str[newLength] = ‘’; is wrong..It will produce indexOutOfBoundException as Size of char Array is length of String.This is not dynamic allocation..

  3. Ashish Singh on November 22, 2014 at 1:01 pm said:

    str[newLength] = ‘’; is wrong..It will produce indexOutOfBoundException as Size of char Array is length of String.This is not dynamic allocation..

  4. Shobhank on December 7, 2014 at 9:56 am said:

    public static String spaceEncode(String str){
    int i = 0;
    while(i<str.length()){
    if(str.charAt(i)==' '){
    str = str.substring(0,i) + "%20" +str.substring(i+1, str.length());
    i = i+3;
    }else{
    i++;
    }
    }
    return str;
    }

  5. I tried with below code and works fine for me :

    public void removeSpaces() {
    System.out.println(“Enter the String “);
    String s = new Scanner(System.in).nextLine();
    // String s1 =”V I K K I ” ;

    System.out.println(s.length());
    String newStr =””;
    for(int i =0; i< s.length() ;i++) {
    char c = s.charAt(i);
    if(c == ' ') {
    // if the word has the space , concat the %20 to the new string
    newStr = newStr+'%'+'2'+'0';
    }
    else {
    // do nothing and proceed to next
    newStr = newStr+s.charAt(i);

    }
    // newStr = newStr + s.charAt(i);

    }
    System.out.println(newStr);

    }

  6. Arun Kumar on May 14, 2015 at 11:41 pm said:

    The code is for C language, as specified in the question. so it will not generate any exception but will work fine.

  7. for java …
    static String replaceSpace(String str)
    {

    str=str.replaceAll(” “, “%20″);
    return str;
    }

  8. Anshdeep Singh on October 7, 2015 at 4:30 pm said:

    Java Code
    public static void replaceSpaces(char[] str,int length){
    int spaceCount = 0,newLength=0,i=0;

    //first scan
    for (i=0;i<length;i++) {
    if(str[i]==' '){
    spaceCount++;
    }
    }
    newLength = length + 2 * spaceCount;

    char[] newArray = new char[newLength+1];
    newArray[newLength] = '';
    int newArrayPosition = 0;

    //second scan
    for (i=0;i<length;i++) {
    if(str[i]==' '){
    newArray[newArrayPosition] = '%';
    newArray[newArrayPosition+1] = '2';
    newArray[newArrayPosition+2] = '0';
    newArrayPosition = newArrayPosition+3;
    }

    else{
    newArray[newArrayPosition] = str[i];
    newArrayPosition++;
    }
    }
    System.out.println(newArray);
    }

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