CS50x Coding Contest 2016 - Word Reverse

reversestring.c

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include "cs50.h"

char* reverseString(char* s);

int main(void) {
    
    char *str = malloc(sizeof(char *) * 200);
    str = GetString(); //get input from user
    
    char *temp = malloc(sizeof(char *) * 200);
    int j = 0;
    
    if (str == NULL)
        return 1;
    
    // loop through string copying to a temp string until a special character or space is found.
    for (int i = 0; i < strlen(str); i++)
    {
        if (isalnum(str[i]))
        {
            temp[j] = str[i];
            j++;
            if (i == strlen(str)-1) //this is a check to see if this is the last character
            {
                reverseString(temp); // reverse temp string and print
                printf("%s", temp);
                j = 0; // reset back to beginning of temp array once we find a special character
                memset(&temp[0], 0, sizeof(temp)); // clear temp array
            }
        }
        else if (!isalnum(str[i]))
        {
            reverseString(temp); // reverse temp string and print
            printf("%s", temp);
            printf("%c", str[i]); // print space/special character
            j = 0; // reset back to beginning of temp array once we find a special character
            memset(&temp[0], 0, sizeof(temp)); // clear temp array
        }
    }
    
    free(str); //free memory
    return 0;
}

char* reverseString(char* s) {
    
    int length = 0, i = 0;
    length = strlen(s);
    char temp[1];
    
    for(i = 0; i < length/2; i++)
    {
        *temp = s[i];
        s[i] = s[length-i-1];
        s[length-i-1] = *temp;
    }
    return s;
}

Problems I encountered:

1. I needed a way to clear my temp array after each swap. Looked that up and got an answer to just clear the memory which worked well.
2. Initially used scanf instead of GetString. Scanf only goes up the first space character which is a problem.
3. If my string didn't end in a special character it wouldn't work, so I needed to add a check to see if we were on the last index of the string and then do the reversing and printing if that was the case.
4. I didn't put in a check for a NULL string.
5. I didn't realize that it wasn't just alpha characters that needed to be switched, but alphanumeric. So instead of isalpha you have to use isalnum.
6. I used my initial reverseString function I created for leetcode problem.