C++ Program to Remove All & Extra Spaces from a String

In this article, you will learn and get code to remove spaces from string using a C++ program. Here are the list of programs on deleting or removing of spaces from entered string by user at run-time:

  • Remove all Spaces from a String
  • Remove only Extra Spaces from a String

In both program, string must be entered by user at run-time.

Remove all Spaces from String

To remove or delete all spaces from a string or a sentence, you have to ask from user to enter the string. And then check for the space, if space gets found, then shift all the character to one index back from where, the space was found, as shown in the program given below:

The question is, write a program in C++ to remove all spaces from string. Here is its answer:

#include<iostream>
#include<stdio.h>
using namespace std;
int main()
{
    char str[200];
    int i=0, j, chk;
    cout<<"Enter the String: ";
    gets(str);
    while(str[i]!='\0')
    {
        chk=0;
        if(str[i]==' ')
        {
            for(j=i; str[j-1]!='\0'; j++)
                str[j] = str[j+1];
            chk = 1;
        }
        if(chk==0)
            i++;
    }
    cout<<"\nString without Spaces: "<<str;
    cout<<endl;
    return 0;
}

This program was build and run under Code::Blocks IDE. Here is its sample run:

C++ program remove spaces from string

Now supply any string say codes cracker . com as input and press ENTER key to remove all spaces from it and print the same string without any space as shown in the snapshot given below:

remove spaces from string c++

The dry run of above program with user input codes cracker . com goes like:

  • When user enters the string, then it gets stored in str variable in a way that:
    • str[0]=c
    • str[1]=o
    • str[2]=d
    • str[3]=e
    • str[4]=s
    • str[5]=' '
    • str[6]=c
    • str[7]=r
    • and so on upto
    • str[18]=m
    • And at last index, that is at 19th index, a null terminated character (\0) automatically gets assigned. So str[19]='\0'
  • Because the initial value of i is 0. Therefore the condition (of while loop) str[i]!='\0' or str[0]!='\0' or c!='\0' evaluates to be true, therefore program flow goes inside the loop
  • Inside the loop, 0 gets initialized to chk. So chk=0
  • Now the condition of if, that is, str[0]==' ' or c==' ' evaluates to be false, therefore program flow evaluates the condition of second if
  • That is, the condition chk==0 or 0==0 evaluates to be true, therefore program flow goes inside the if's body, and increments the value of i. So i=1
  • Now program flow evaluates the condition of while loop again. That is, the condition str[i]!='\0' or str[1]!='\0' or o!='\0' evaluates to be true again, therefore program flow goes inside the loop again
  • This process continues, until the condition of while loop evaluates to be false
  • If any space occurs, then from the index where a space gets found, we've shifted all the characters to one index back. For example, if a space is found at index no.5, then:
    • character at 6th index gets moved to 5th index
    • character at 7th index gets moved to 6th index
    • character at 8th index gets moved to 7th index
    • and so on
  • After shifting all the characters, we've initialized 1 to chk. To check its value, whether it holds its previous value (0) or not. If it holds its previous value, then increments the value of i, otherwise, don't increment the value of i, to start from the same (previous) index, or last evaluation's index
  • Because through above example of shifting characters, we've shifted the character at 6th index to 5th index, that is now a new character. That is why, we've used chk variable to check and increment i's value
  • In this way, all the spaces gets removed from the string, str. So just print its value after performing the task

Remove Extra Spaces from String

This program removes only extra spaces from the given String. For example, if there are more than one spaces available between any two words, then all the spaces except one, gets removed. Let's have a look at the program:

#include<iostream>
#include<stdio.h>
#include<string.h>
using namespace std;
int main()
{
    char str[200];
    int i, j, len;
    cout<<"Enter the String: ";
    gets(str);
    len = strlen(str);
    for(i=0; i<len; i++)
    {
        if(str[0]==' ')
        {
            for(i=0; i<(len-1); i++)
                str[i] = str[i+1];
            str[i] = '\0';
            len--;
            i=-1;
            continue;
        }
        if(str[i]==' ' && str[i+1]==' ')
        {
            for(j=i; j<(len-1); j++)
            {
                str[j] = str[j+1];
            }
            str[j] = '\0';
            len--;
            i--;
        }
    }
    cout<<"\nString without Extra Spaces: "<<str;
    cout<<endl;
    return 0;
}

Here is the initial output produced by this program:

remove extra spaces from string c++

Now supply any string that contains more than one spaces between two words, and press ENTER to remove extra spaces from the given string and print the new string as shown in the snapshot given below:

c++ remove extra spaces from string

Same Program in Other Languages

C++ Online Test


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