use the recursion only

[lam814]

I have been thinking about task 4 and 5 for many days, but it has not solved the problem, can you help me?
the question of Task 4
https://imgur.com/OBZ1WV3

the question of Task 5
https://imgur.com/D3or4W9

* Note:
* - DO NOT change any of the function headers given
* - DO NOT use any loops
* - DO NOT use any global variables or add additional libraries.
* - You can add helper function(s) if needed.
*/

#include <iostream>

using namespace std;

// Constants

// NULL character. This is the last char of all C Strings
const char END = '\0';

// Single quotation character '
const char SQUOTE = '\'';

// Double quotation character "
const char DQUOTE = '\"';

// Error. Used in Task 2 and 3
const int ERROR = -1;

// Practice Task: Task 0 (Not Graded)
unsigned int recursive_strlen(const char line[], int start)
{


	if(line[start]!= END){
		recursive_strlen(line,++start);
	}
	else if(line[start]== END){
		return start;
}

}

// Normal Task: Task 1
unsigned int count_dquotes(const char line[], int start)
{
    int x =  recursive_strlen(line,0);

	if(x>start){
		if(line[start]== '"'){
            if(start==(x-1)){return 1;}
            else{return 1+count_dquotes(line,start+1);}
		}

		else{
			if(start==(x-1)){return 0;}
			else{return 0+count_dquotes(line,start+1);}
		}
	}
}

// Normal Task: Task 2
int find_first_dquote(const char line[], int start)
{

if(recursive_strlen(line,start)==0||count_dquotes(line,start)==0){return ERROR;}
else if(line[start]!= END){
	if(line[start]=='"'){return start;}
	else{find_first_dquote(line,start+1);}

	}
}


// Normal Task: Task 3
int count_chars_in_matched_dquote(const char line[], int start)
{

    int len = recursive_strlen(line,0);
    if(start==0 && count_dquotes(line,start)%2==1 ){
       return -1;
			}
		else if(start==0 &&count_dquotes(line,start)==0){
			    return 0;
			}

		else if(start<len && count_dquotes(line,start)!=0){

		    int x = find_first_dquote(line,start);
		    int y = find_first_dquote(line,1+x)-x-1;

		    return y + count_chars_in_matched_dquote(line,find_first_dquote(line,1+x)+1);
		}


}


// Challenging Task: Task 4
bool check_quotes_matched(const char line[], int start)
{
	
}

// Challenging Task: Task 5
unsigned int length_of_longest_consecutive_dquotes(const char line[], int start)
{
	


}


// DO NOT WRITE ANYTHING AFTER THIS LINE. ANYTHING AFTER THIS LINE WILL BE REPLACED

const int MAX_LENGTH = 1000;

int main()
{
	int option = 0;
	char line[MAX_LENGTH];

	do {
		cout << "Options:" << endl;
		cout << "0:  Test recursive_strlen()" << endl;
		cout << "1:  Test count_dquotes()" << endl;
		cout << "2:  Test find_first_dquote()" << endl;
		cout << "3:  Test count_chars_in_matched_dquote()" << endl;
		cout << "4:  Test check_quotes_matched()" << endl;
		cout << "5:  Test length_of_longest_consecutive_dquotes()" << endl;
		cout << "-1: Quit" << endl;

		cin >> option;
		cin.ignore();

		switch (option) {
			case 0:
			cout << "Testing recursive_strlen()" << endl;
			cout << "Enter line: ";
			cin.getline(line, MAX_LENGTH);
			cout << recursive_strlen(line, 0) << endl;
			break;

			case 1:
			cout << "Testing count_dquotes()" << endl;
			cout << "Enter line: ";
			cin.getline(line, MAX_LENGTH);
			cout << count_dquotes(line, 0) << endl;
			break;

			case 2:
			cout << "Testing find_first_dquote()" << endl;
			cout << "Enter line: ";
			cin.getline(line, MAX_LENGTH);
			cout << find_first_dquote(line, 0) << endl;
			break;

			case 3:
			cout << "Testing count_chars_in_matched_dquote()" << endl;
			cout << "Enter line: ";
			cin.getline(line, MAX_LENGTH);
			cout << count_chars_in_matched_dquote(line, 0) << endl;
			break;

			case 4:
			cout << "Testing check_quotes_matched()" << endl;
			cout << "Enter line: ";
			cin.getline(line, MAX_LENGTH);
			cout << check_quotes_matched(line, 0) << endl;
			break;

			case 5:
			cout << "Testing length_of_longest_consecutive_dquotes()" << endl;
			cout << "Enter line: ";
			cin.getline(line, MAX_LENGTH);
			cout << length_of_longest_consecutive_dquotes(line, 0) << endl;
			break;

			default:
			break;
		}

		cout << endl;

	} while (option != -1);

	return 0;
}

[jonnin]

how do you count quotes recursively?
if its not the end of the string, call yourself.
after calling yourself, return a 1 or a 0 if its a quote or not.
you are taking a running sum of that, a static variable is one way to do that (remember to reset it to zero when doing a new block of text!).
if its an even#, your quotes matched (?) right?

[Enoizat]

OBZ1WV3:

Challenging Tasks 
Task 4
bool check_quotes_matched(const char line[], int start)
- This function checks whether quotation characters (single and double quotation
  characters) in the string (line) are matched.
- Return:
    - true if all quotation characters are matched, or no quotation characters
      are found.
    - false otherwise.

Hint
- Write two helper functions to handle:
    1. When a single quotation character is read.
    2. When a double quotation character is read.
- These three functions should call each other.

| Sample Input (line)  | Return Value  |
|----------------------|---------------|
| (Empty)              |     true      |
| COMP2011             |     true      |
| 'COMP2011'           |     true      |
| Hello " World        |     false     |
|  " 'Hello World' "   |     true      |
| "A single quote: '"  |     true      |
| "A'A'A'A"            |     true      |
| '"A""A"              |     false     |

D3or4W9:

Task 5
unsigned int length_of_longest_consecutive_dquotes(const char line[], int start)
- This function finds the length of the longest consecutive sequence of double
  quotation characters in the string (line).
• It returns the length of the longest consecutive sequence of double quotation
  characters.

Hint
- Write a recursive helper function that takes additional parameters.

|Sample Input (line)  | Return Value |
|---------------------|--------------|
|(Empty)              |      0       |
| COMP2011            |      0       |
| "COMP2011"          |      1       |
| Hello " World       |      1       |
| """Hello World"""   |      3       |
| AAAAAA""BBB         |      2       |
| """AAA""""""        |      6       |
| """""BBBBBBBBB"""   |      5       |

Wouldn’t it have been simpler to just link to the webpages where these exercises come from?
What kind of help do you want?

[mbozzi]

Task 4:

bool check_quotes_matched(char const* s);

bool in_quote(char const* s, char q)
{ 
  return (*s == q   )? check_quotes_matched(s + 1)
       : (*s == '\0')? false : in_quote(s + 1, q);
}

bool check_quotes_matched(char const* s)
{
  return (*s == '"' )? in_quote(s + 1, '"' )
       : (*s == '\'')? in_quote(s + 1, '\'')
       : (*s == '\0')? true : check_quotes_matched(s + 1);
}

[dutch]

That's pretty good, but I assumed it was supposed to be able to handle nested quotes, like:

one "two 'three' four" five

[mbozzi]

I assumed it was supposed to be able to handle nested quotes

I thought so myself, at first, but there's this test case:
| "A'A'A'A" | true |