Reverse word order in sentence - c++

Question

I'm having difficulty creating a function that reverse the order of the sentence around. I've read many functions on how to recursively reverse the letters around and I have successfully done so, but I do not want to reverse the letters in the words. I want to reverse the placement of the words in the sentence.
Example would be:
This is a sentence.
sentence. a is This
This is my code so far. How do I go from reversing order of letters of the entire sentence to placement order of words in a sentence?
The output of the current code would provide: !dlroW olleH
void reverse(const std::string str)
{
int length = str.size();
if(length > 0)
{
reverse(str.substr(0,length-1));
std::cout << str[0];
}
}
Edit: Additional question. If this was a char array would the logic be different?

Answer 1

Simplify your logic by using a std::istringstream and a helper function. The program below works for me.
#include <sstream>
#include <iostream>
void reverse(std::istringstream& stream)
{
std::string word;
if ( stream >> word )
{
reverse(stream);
std::cout << word << " ";
}
}
void reverse(const std::string str)
{
std::istringstream stream(str);
reverse(stream);
std::cout << std::endl;
}
int main(int argc, char** argv)
{
reverse(argv[1]);
return 0;
}

Answer 2

// Pass string which comes after space
// reverse("This is a sentence.")
// reverse("is a sentence.")
// reverse("a sentence.")
// reverse("sentence.")
// will not find space
// start print only word in that function
void reverse(const std::string str)
{
int pos = str.find_first_of(" ");
if (pos == string::npos) // exit condition
{
string str1 = str.substr(0, pos);
cout << str1.c_str() << " " ;
return;
}
reverse(str.substr(pos+1));
cout << str.substr(0, pos).c_str() << " ";
}
Simple to understand:
void reverse(const std::string str)
{
int pos = str.find_first_of(" ");
if (pos != string::npos) // exit condition
{
reverse(str.substr(pos + 1));
}
cout << str.substr(0, pos).c_str() << " ";
}

Answer 3

std::vector<std::string> splitString(const std::string &s, char delim) {
std::stringstream ss(s);
std::string item;
std::vector<std::string> tokens;
while (getline(ss, item, delim)) {
tokens.push_back(item);
}
return tokens;
}
void reverseString(const std::string& string) {
std::vector<std::string> words = splitString(string, ' ');
auto end = words.rend();
for (auto it = words.rbegin(); it <= end; it++) {
std::cout << *it << std::endl;
}
}
reverseString("This is a sentence.");

Answer 4

You can split input and print them in inverse order
Or if you want to use recursive structure just move the cout after calling a function like this:
void reverse(const std::string str)
{
std::stringstream ss(str);
std::string firstWord, rest;
if(ss >> firstWord)
{
getline(ss , rest);
reverse(rest);
std::cout << firstWord << " ";
}
}

Answer 5

I am not a C++ programmer, but I would create another array (tempWord[ ]) to store individual word.
Scan each word and store them into tempWord array. In your case, the words are separated by space, so:
a.get the index of the next space,
b substring to the index of the next space and
c. you should get {"This", "is", "a", "sentence."}
Add them up again reversely:
a. loop index i from "tempWord.length -1" to "0"
b. new String = tempWord[i]+" ";
print out result.