A function to add two 50-digit numbers and return it

`string addBigNumbers(string n1, string n2){ string result = ""; int len1 = n1.size(); int len2 = n2.size(); if (len1 == 0) return n2; if (len2 == 0) return n1; int carry = 0; int a, b, sum; int i = len1 - 1, j = len2 - 1; while (i >= 0 || j >= 0 || carry > 0) { a = 0; b = 0; if (i >= 0) a = n1[i] - '0'; if (j >= 0) b = n2[j] - '0'; sum = a + b + carry; if (sum >= 10) carry = 1; else carry = 0; result.push_back(sum % 10 + '0'); i--; j--; } reverse`