Example: Remove Non-Alphabets (In-Place) in C

// Remove Non-Alphabets (In-Place)
#include <stdio.h>
#include <string.h> // For strlen (not strictly needed for this loop, but good for general string ops)
#include <ctype.h>  // For isalpha

int main() {
    char myString[] = "H3ll0, W0rld! 123";
    int readPtr, writePtr;

    // Step 1: Initialize writePtr to 0, which will point to the next available position for a valid character
    writePtr = 0;

    // Step 2: Iterate through the string using readPtr
    for (readPtr = 0; myString[readPtr] != '\0'; readPtr++) {
        // Step 3: Check if the character is an alphabet
        if (isalpha(myString[readPtr])) {
            // Step 4: If it's an alphabet, copy it to the writePtr position
            myString[writePtr] = myString[readPtr];
            writePtr++; // Move writePtr forward
        }
    }
    // Step 5: Null-terminate the modified string at the writePtr position
    myString[writePtr] = '\0';

    printf("Original string (after modification): %s\n", myString);

    return 0;
}