Count matching letters once-CodePudding

I'm creating a kid's learning tool that has a form which matches 4 letters to a word.

I want to count the number of character matches in a word. But it counts duplicates of letters as 2 instead of 1. For example if the word is "loot", and the user submits "flop", the matching letters are 3 instead of 2, because it's counting "o" twice. How do I fix this? Many thanks

       function countMatching(str1, str2) {
            var c = 0;

            for (var i = 0; i < str1.length; i  ) {

              if (str2.includes(str1[i]))
                c  = 1;
                
            }
            matchingLetters = c;
          }

CodePudding user response：

I made an alternative version of @cmgchess' answer, which creates an array of the actual solution of letters to still guess, and removes each letter as it is encountered in the entered solution.

let matchingLetters;

function countMatching(str1, str2) {
            var c = 0;
            str1Arr = str1.split('');
            
            for (var i = 0; i < str2.length; i  ) {

              if (str1Arr.includes(str2[i])) {
                c  = 1;
                str1Arr.splice(str1Arr.indexOf(str2[i]), 1);
              }
                
            }
            matchingLetters = c;
          }
          
          
countMatching('loot', 'boot') 
console.log(matchingLetters)

CodePudding user response：

A possible approach using Sets. I converted the string into a set and back to an array so if str1 is loot then str1Set will be ['l','o','t']. The rest is the same

let matchingLetters;

function countMatching(str1, str2) {
            var c = 0;
            str1Set = [...new Set([...str1])]
            str2Set = [...new Set([...str2])]
            
            for (var i = 0; i < str1Set.length; i  ) {

              if (str2Set.includes(str1Set[i]))
                c  = 1;
                
            }
            matchingLetters = c;
          }
          
          
countMatching('loot', 'flop') 
console.log(matchingLetters)

CodePudding user response：

function countMatching(str1, str2) {
            var c = [];

            for (var i = 0; i < str1.length; i  ) {

              if (str2.includes(str1[i]))
                  if (!c.includes(str1[i])) c.push(str1[i])
                
            }
            matchingLetters = c.length;
          }

I'm writing on a tab, so there might be mistakes

What I did is that I made c to be a list that contains each character shared between the two strings. And a new character is pushed into c only if the character doesn't exist in it, hence making it a list of unique characters.

Then you can get the length of the list or you can even use the list for other purposes