Q) How does one reverse the characters in a string (e.g. “god” becomes “dog”). This classic computer science question can then be extended to the more interesting question: how does one reverse all the characters in a sentence, but keeping the actual words in place (e.g. “cat chases dog” becomes “dog chases cat”)? A) Here’s the full answer (and …

ReverseCharactersInAnyString

reverseString(char *array, int start, int end)
{
    int rightIndex = end;
    for(int leftIndex = start; leftIndex < rightIndex; leftIndex++)
    {
        char swapChar = array(rightIndex);
        array(rightIndex) = array(leftIndex);
        array(leftIndex) = swapChar;
        rightIndex--;
    }
}

reverseTheEntireString(char *wholeString)
{
    // reverse the entire string....
    reverseString(wholeString, 0, strlen(wholeString));
    
    // then step through the entire string looking for either the null
    // terminator or a space... then reverse everything within the
    // leftIndex & rightIndex range
    int leftIndex = 0;
    for(int rightIndex = 0; rightIndex <strlen(wholeString); rightIndex++)
    {
        if((rightIndex == ' ') || (rightIndex == 0))
        {
            reverseString(wholeString, leftIndex, rightIndex-1);
            leftIndex = rightIndex+1; // go beyond the space
        }
    }
}