Leetcode[string]: Add Binary

Given binary strings, return their sum (also a binary string).
For example,
A = "11"
b = "1"
Return "100".

My C + + implementation code is as follows:

String Addbinary (String A, string b) {    string sum;    int carry = 0;    for (int i = A.size ()-1, J = b.size ()-1; I >= 0 | | J >= 0;-I.,--J) {        string Bitadd ("0");        int src1 = (i >= 0? A[i]-' 0 ': 0);        int src2 = (J >= 0? B[j]-' 0 ': 0);        Bitadd[0] + =  (Src1 + SRC2 + carry) & 1;        Carry = ((Src1 + SRC2 + carry) & 2)? 1:0;        sum = Bitadd + sum;    }    if (carry) {        string S ("1");        sum = s + sum;    }    return sum;}

Leetcode[string]: Add Binary