The sum of two n digits written by C ++

# Include <iostream>
# Include <string>
Int main ()
{
Using namespace STD;
String A, B;
Cout <Endl <"input number :";
Cin>;
Cout <"Enter the number B :";
Cin> B;
Int DH/* used to save the sum of each digit in a B and */
, Yu = 0/* is used to save the value to carry */
, AZ = A. Size ()-1, Bz = B. Size ()-1;/* measure the length of a B string minus 1 because the array starts from 0 */
Int bjab = Az> BZ? AZ: Bz; // calculate the length of the string a and B.

Char * P = new char [bjab + 3]; // The requested space for storing the final sum

If (P = NULL)
{
Cout <"insufficient memory ";
Return 0;
}
Int I = 0, Vc = 0, K = 0, JL = 0;
For (I; I <= bjab + 2; I ++)
{

If (! (A [AZ]> = '0' & A [AZ] <= '9' & B [BZ]> = '0' & B [BZ] <= '9 '))
{
Cout <Endl <"the number you entered contains invalid characters! The program will exit "<Endl;
Delete [] P;
Exit (1 );

}
DH = (a [AZ]-'0') + (B [BZ]-'0'); // convert each character in a B to a number and then add it together
P [VC ++] = (DH + Yu) % 10) + '0'; // save DH and single digit
If (DH + Yu = 10) Yu = 1; // this parameter is used to remove the case where DH equals 9 Yu equals 1 and there is no remainder.
Else Yu = DH/10;

If (AZ = 0) A [AZ] = '0'; // when string a is shorter than string B, add 0 if string a is shorter than string B.
Else AZ --;
If (Bz = 0) B [BZ] = '0'; // same as above
Else BZ --;
}
Cout <Endl <"the length of number A is :"
<A. Size () <Endl <"the length of digit B is :"
<B. Size () <Endl;
Cout <Endl <"A + B = ";
If (P [VC-1] = '0' & P [vc-2] = '0') k = vc-3; // remove the case where there is no carry before 0
Else if (P [VC-1] = '0') k = vc-2;
Else
K = VC-1;
For (K; k> = 0; k --) // output characters from the back
Cout <p [k];
Cout <Endl;
Delete [] P;
Return 0;
}