Stuck with an infinite loop and whitespaces detection c++ - c++

Question

This is the question that needs to be implemented:
Write a C++ program that stops reading a line of text when a period is
entered and displays the sentence with correct spacing and capitalization. For this program, correct spacing means only one space between words, and all letters should be lowercase, except the first letter. For example, if the user enters the text "i am going to Go TO THe moVies.", the displayed sentence should be "I am going to go to the movies."
I have written my piece of code which looks like this:
// Processing a sentence and verifying if it is grammatically correct or not (spacing and capitalization)
//#include <stdio.h>
//#include <conio.h>
#include <iostream>
#include <string>
using namespace std;
int main()
{
string sentence;
cout << "Enter the sentence: ";
getline(cin, sentence);
int len = sentence.length();
// Dealing with capitalizations
for (int j = 0; j <= len; j++)
{
if (islower(sentence[0]))
sentence[0] = toupper(sentence[0]);
if(j>0)
if(isupper(sentence[j]))
sentence[j] = tolower(sentence[j]);
}
int space = 0;
do
{
for (int k = 0; k <= len; k++)
{
if(isspace(sentence[k]))
{
cout << k << endl;
int n = k+1;
if(sentence[n] == ' ' && n <=len)
{
space++;
cout << space <<endl;
n++;
cout << n <<endl;
}
if(space!= 0)
sentence.erase(k,space);
cout << sentence <<endl;
}
}
len = sentence.length();
//cout << len <<endl;
} while (space != 0);
}
With this I was able to deal with capitalization issue but problem occurs when I try to check for more than one whitespace between two words. In the do loop I am somehow stuck in an infinite loop.
Like when I try and print the length of the string (len/len1) in the first line inside do-while loop, it keeps on running in an infinite loop. Similarly, when I try and print the value of k after the for loop, it again goes into infinite loop. I think it has to do with my use of do-while loop, but I am not able to get my head around it.
This is the output that I am receiving.

Answer 1

there are a few different issues with this code, but i believe that the code below addresses them. hopefully this code is readable enough that you can learn a few techniques. for example, no need to capitalize the first letter inside the loop, do it once and be done with it.
the usual problem with infinite loops is that the loop termination condition is never met--ensure that it will be met no matter what happens in the loop.
#include <iostream>
#include <string>
using namespace std;
int main() {
string sentence;
cout << "Enter the sentence: ";
getline(cin, sentence);
int len = sentence.find(".", 0) + 1; // up to and including the period
// Dealing with capitalizations
if (islower(sentence[0]))
sentence[0] = toupper(sentence[0]);
for (int j = 1; j < len; j++)
if(isupper(sentence[j]))
sentence[j] = tolower(sentence[j]);
// eliminate duplicate whitespace
for (int i = 0; i < len; i++)
if (isspace(sentence[i]))
// check length first, i + 1 as index could overflow buffer
while (i < len && isspace(sentence[i + 1])) {
sentence.erase(i + 1, 1);
len--; // ensure sentence decreases in length
}
cout << sentence.substr(0, len) << endl;
}

Answer 2

Here goes
std::string sentence;
std::string new_sentence;
std::cout << "Enter the sentence: ";
std::getline(std::cin, sentence);
bool do_write = false; // Looking for first non-space character
bool first_char = true;
// Loop to end of string or .
for (unsiged int i = 0; i < sentence.length() && sentence[i] != '.'; ++i) {
if (sentence[i] != ' ') { // Not space - good - write it
do_write = true;
}
if (do_write) {
new_sentence += (first_char ? toupper(sentence[i]) : tolower(sentence[i]);
first_char = false;
}
if (sentence[i] == ' ') {
do_write = false; // No more spaces please
}
}
if (i < sentence.length()) { // Add dot if required
new_sentence += '.';
}