string strings[10];
void split(string s){
    int curr=0,start=0,end=0,i=0;
    
    while(i<=len(s)){
        if(s[i]==' ' or i == len(s)){
            end = i;
            string sub;
            sub.append(s,start,end-start);
            strings[curr] = sub;
            start = end   1;
            curr  = 1 ; 
        }
        i  ;
    }
}

for example if the input is " computer laptop screen desktop mouse " then the output string should be: computer laptop screen desktop mouse

I have successfully tried using loops but failed using recursion, can anyone help me solve split() using recursion. Thank you

CodePudding user response：

This solution assumes you want only words from the string to enter your array and that you want to split on some predetermined delimiter like <space>' ' or <dash>'-'.

If you need to keep the void function signature, here is one:

void split_rec(string str_array[], size_t arr_index,
               string s, char delimiter) {
    if (s == "") {
        return;
    }
    size_t delim_index = s.find(delimiter);
    string str_to_add = s.substr(0, delim_index);
    // This step filters out extra delimiters that would cause empty strings.
    if (str_to_add != "") {
        str_array[arr_index  ] = str_to_add;
    }
    // find() returns string::npos if it doesnt find delimiter.
    if (delim_index == string::npos) {
        return;
    } else {
        split_rec(str_array, arr_index, s.substr(delim_index   1), delimiter);
    }
}

But I would recommend returning the size of the array so you communicate what the function is doing more accurately. Like this:

size_t split_rec(string str_array[], size_t arr_index,
                 string s, char delimiter) {
    if (s == "") {
        return arr_index;
    }
    size_t delim_index = s.find(delimiter);
    string str_to_add = s.substr(0, delim_index);
    if (str_to_add != "") {
        str_array[arr_index  ] = str_to_add;
    }
    if (delim_index == string::npos) {
        return arr_index;
    }
    return split_rec(str_array, arr_index, s.substr(delim_index   1), delimiter);
}

Then the call is like this:

string strings[10];
// I left some extra spaces in this string.
string str = " computer  laptop screen desktop mouse  ";
size_t strings_len = split_rec(strings, 0, str, ' ');
cout << "Array is length " << strings_len << endl;
for (size_t i = 0; i < strings_len; i  ) {
    cout << strings[i] << endl;
}

Array is length 5
computer
laptop
screen
desktop
mouse