Linked list string sorting issue

Question

The problem is if I enter 1, then 2 and 123. It will sort 1,123,2.
How do i make it sort 1,2,123

Item is the Records that was created. Runner is the traverser.

struct Records {
string Name;
string ID;
char Gender;
string Phone_Num;
Records *Next;
};

void SortRecords(Records* Item, Records* head, Records** Set_Head){
Records* Runner = head;

if (head == NULL){
    *Set_Head = Item;
}else if (Item->ID<head->ID){
    Item->Next=head;
}else{
    while(Item->ID>head->ID){
        if(Item->ID > Runner->ID && Runner->Next==NULL){
            Runner->Next=Item;
            break;
        }else if(Item->ID<Runner->Next->ID){
            Item->Next=Runner->Next;
            Runner->Next=Item;
            Runner=Item;
            cout<<Runner->Next->Name<<endl;
            break;
        }else{
            Runner=Runner->Next;
        }

    }

}

If string is really std::string then you're programming in C++ and should not use the C language tag. — Some programmer dude
– Some programmer dude, Commented Apr 4, 2018 at 4:39
That also explains the sorting problem you have, as strings when compared are compared lexicographically, where any string beginning with e.g. '1' will be smaller than any other string beginning with e.g. '2'. — Some programmer dude
– Some programmer dude, Commented Apr 4, 2018 at 4:41
Store your ID in an int or convert it into an int when doing the comparison. Look up how to parse strings into ints if you don't know how. — user9254539
– user9254539, Commented Apr 4, 2018 at 4:44
Please check the description of tags before applying them. The "c" tag explicitly tells you when it can be combined with "c++" and when not. — Ulrich Eckhardt
– Ulrich Eckhardt, Commented Apr 4, 2018 at 4:46

Yola · Accepted Answer · 2018-04-04 04:45:09Z

1

You can use std::stoi to compare integers not strings:

std::stoi(Item->ID) < std::stoi(Runner->Next->ID)

You might actually want to store ID as integer, not string.

If you ID can be, say "123AB", then you can extract number with:

string str = "123AB";
size_t last_index = str.find_last_of("0123456789");
string result = str.substr(0, last_index + 1); // result = "123";

answered Apr 4, 2018 at 4:45

Yola

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