Remove spaces from a string in C

Understanding String Manipulation

Removing spaces from a string means eliminating all whitespace characters.

We will explore three different methods to achieve this in C.

Method 1: Using a Loop

This method iterates through the string and copies only non-space characters.

#include <stdio.h>
#include <string.h>

void removeSpaces(char *str) {
    int count = 0;
    for (int i = 0; str[i]; i++)
        if (str[i] != ' ')
            str[count++] = str[i];
    str[count] = '\0';
}

int main() {
    char str[] = "Hello World!";
    removeSpaces(str);
    printf("Filtered String: %s", str);
    return 0;
}
            

Method 2: Using Recursion

This method removes spaces recursively.

#include <stdio.h>

void removeSpacesRecursive(char *str, int index, int count) {
    if (str[index] == '\0') {
        str[count] = '\0';
        return;
    }
    if (str[index] != ' ')
        str[count++] = str[index];
    removeSpacesRecursive(str, index + 1, count);
}

int main() {
    char str[] = "C programming";
    removeSpacesRecursive(str, 0, 0);
    printf("Filtered String: %s", str);
    return 0;
}
            

Method 3: Using Pointers

This method uses pointers to remove spaces efficiently.

#include <stdio.h>

void removeSpacesPointer(char *str) {
    char *i = str, *j = str;
    while (*i) {
        if (*i != ' ')
            *j++ = *i;
        i++;
    }
    *j = '\0';
}

int main() {
    char str[] = "Remove spaces";
    removeSpacesPointer(str);
    printf("Filtered String: %s", str);
    return 0;
}