Reverse each word of a string in C
I have a few issues with in your code:


Consistency in naming - use either camelCase or not_camel_case but don't
mix
consistency in braces.  The opening brace for a function goes in the first
column.
word_start_index and word_end_index should take a const parameter
word_start_index is the same as strspn(string, " "); or if you are also
looking for punctuation, strspn(string, " \t\n.,;:"); 
word_end_index - as for word_start_index but use strcspn (note the
'c')
word_end_index as a function (ie not in your context) fails for an empty
string or a string starting with a space  (it returns the char before the
string starts).
variable test in main() is misnamed. I would prefer something that shows it
is a string.
the test while (test != '\0') in main() is wrong - should be *test !=
'\0'.
Your loop always exits from the break
no return or parameters in main()


Also, arguably the position of the stars in your pointers is wrong.  I prefer char* p to be written char *p, which makes it clear that it is p that takes the star. Consider code such as char* a, b;. This is bad because it gives the impression that b is a pointer.