Need a program to reverse the words in a string - string

Question

I asked this question in a few interviews. I want to know from the Stackoverflow readers as to what should be the answer to this question.
Such a seemingly simple question, but has been interpreted quite a few different ways.

Answer 1

if your definition of a "word" is a series of non-whitespace characters surrounded by a whitespace character, then in 5 second pseudocode you do:
var words = split(inputString, " ")
var reverse = new array
var count = words.count -1
var i = 0
while count != 0
reverse[i] = words[count]
count--
i++
return reverse

Answer 2

If you want to take into consideration also spaces, you can do it like that:
string word = "hello my name is";
string result="";
int k=word.size();
for (int j=word.size()-1; j>=0; j--)
{
while(word[j]!= ' ' && j>=0)
j--;
int end=k;
k=j+1;
int count=0;
if (j>=0)
{
int temp=j;
while (word[temp]==' '){
count++;
temp--;
}
j-=count;
}
else j=j+1;
result+=word.substr(k,end-k);
k-=count;
while(count!=0)
{
result+=' ';
count--;
}
}
It will print out for you "is name my hello"

Answer 3

Taken from something called "Hacking a Google Interview" that was somewhere on my computer ... don't know from where I got it but I remember I saw this exact question inside ... here is the answer:
Reverse the string by swapping the
first character with the last
character, the second with the
second-to-last character, and so on.
Then, go through the string looking
for spaces, so that you find where
each of the words is. Reverse each of
the words you encounter by again
swapping the first character with the
last character, the second character
with the second-to-last character, and
so on.

Answer 4

This came up in LessThanDot Programmer Puzzles

Answer 5

#include<stdio.h>
void reverse_word(char *,int,int);
int main()
{
char s[80],temp;
int l,i,k;
int lower,upper;
printf("Enter the ssentence\n");
gets(s);
l=strlen(s);
printf("%d\n",l);
k=l;
for(i=0;i<l;i++)
{
if(k<=i)
{temp=s[i];
s[i]=s[l-1-i];
s[l-1-i]=temp;}
k--;
}
printf("%s\n",s);
lower=0;
upper=0;
for(i=0;;i++)
{
if(s[i]==' '||s[i]=='\0')
{upper=i-1;
reverse_word(s,lower,upper);
lower=i+1;
}
if(s[i]=='\0')
break;
}
printf("%s",s);
return 0;
}
void reverse_word(char *s,int lower,int upper)
{
char temp;
//int i;
while(upper>lower)
{
temp=s[lower];
s[lower]=s[upper];
s[upper]=temp;
upper=upper-1;
lower=lower+1;
}
}

Answer 6

The following code (C++) will convert a string this is a test to test a is this:
string reverseWords(string str)
{
string result = "";
vector<string> strs;
stringstream S(str);
string s;
while (S>>s)
strs.push_back(s);
reverse(strs.begin(), strs.end());
if (strs.size() > 0)
result = strs[0];
for(int i=1; i<strs.size(); i++)
result += " " + strs[i];
return result;
}
PS: it's actually a google code jam question, more info can be found here.