415. Add Strings

The simplest part of the Bitinteger

Put two strings in turn, from back to forward, the place to learn is that for while conditions can be set to,index1< Len1 | | Index2 < Len2.

The Index1 < len1 and index2 <len2 are then processed internally, so there is no need to write a separate loop for one of the early end cases.

1      Publicstring AddStrings (String num1, String num2) {2         if(NUM1 = =NULL) {3             returnnum2;4         }5         if(num2 = =NULL) {6             returnNUM1;7         }8StringBuilder SB1 =NewStringBuilder (NUM1);9StringBuilder SB2 =NewStringBuilder (num2);Ten         intLen1 =num1.length (); One         intLen2 =num2.length (); A sb1.reverse (); - sb2.reverse (); -StringBuilder SB =NewStringBuilder (); the         intindex1 = 0; -         intIndex2 = 0; -         intCarry = 0; -          while(Index1 < Len1 | | Index2 <len2) { +             intCur =carry; -             if(Index1 <len1) { +Cur + = Sb1.charat (index1++)-' 0 '; A             } at             if(Index2 <len2) { -Cur + = Sb2.charat (index2++)-' 0 '; -             } -             if(Cur > 9) { -Cur%= 10; -Carry = 1; in}Else { -Carry = 0; to             } + sb.append (cur); -         } the         if(Carry = = 1) { *Sb.append (1); $         }Panax Notoginseng         returnsb.reverse (). toString (); -}

415. Add Strings