Remove those spaces!!

Its been a long time since I have posted something new and useful...well have been really busy with life!!

Here is a code I wrote for fun...it removes all the multiple tabs and blank spaces in a string.

Feel free to use it, but do give credit to the Author :)
And if you find any issues...or feel like giving some feed back...you are most welcome!!

/*
 * Date: 10th December 2006
 * Simple Utility code written by hundredrabh
 * It simply removes more than 4 spaces and tab stops
 * from the input string and replaces them with space.
 * You can download and play with the code
 * But please do give due credit to the author for his efforts!!
 * Happy Coding
*/

#include "stdio.h" 
#include "stdlib.h" 

/* Function declaration and defination */

/* char* enterString(char*)
 * Accepts a char pointer, to return the input string
 * returns a pointer to the input string, and this pointer needs to be freed by the user!
 * Error checking needs to be added for return values and realloc
// TODO - Enhance it for buffered reading/writing
// As realloc is slow....
 */
char*
enterString(char* str)
{
    char ch;
    int len = 0;
    while(10 != (ch = fgetc(stdin)))
    {
        if(0 == (len % 512)) {
            str = (char*)realloc(str, len + 513); // TODO - Need Error Checking here...
        }
        *(str + len) = ch;
        *(str + len + 1) = '\0'; // adding the null termination as realloc does not return 0ed memory..so EOS determination is difficult.
        ++len;
    }
    return str; // This needs to be freed by the user
}

/* End of enterString(char*) */

/* DETAB
 * void detab(const char*)
 * returns a void, accepts a char*
 * remove all the tab spaces or spaces which are in multiples of 4 from the string
 * Spaces before and after a tab will be considered as continuous!!
 *
*/
void
detab(char* str)
{
    char* dummyRetStr = str;
    int spaces = 0;
    while(*str)
    {
        switch(*str)
        {
            case '\t': // Remove the tab       
                *str = ' ';
                ++spaces;
                break;
            // check for 4 spaces together   
            case ' ' :
                ++spaces;
                break;
            default  :
                spaces = 0;
                break;
        }
        *dummyRetStr++ = *str++;
        if(spaces == 4)    dummyRetStr -=3, spaces =1; // Remove 4 spaces occuring together!
    }
    *dummyRetStr = '\0'; // null terminate the  modified string
}


int
main()
{
    char *inp = 0;
    printf("Enter the string \n");
   
    inp = enterString(inp); // Free inp, it has been malloced
    detab(inp);

    printf("You entered .... %s\n", inp);
    realloc(inp, 0);
    return 0;
}