Subtraction of large numbers 2 -- add the leading zero before the shorter number to align the trim bit

 

 # Define _ Crt_secure_no_warnings # Include <Stdio. h> # Include < String . H> Int  Main (){  Char Str1 [ 255 ], Str2 [ 255  ];  Int Num1 [255 ] = { 0 }, Num2 [ 255 ] = { 0 }; //  Used to store the subtrahend and subtrahend, and the shorter subtrahend Add the leading zeros.      Int Dvalue [ 255 ] = { 0  };  Int  Length1, leng2, length;  Int  I, J;  Int Neg_flag = 0 ; //  A negative flag      Int Flag = 0 ; //  Borrow sign  Gets (str1); gets (str2); length1 = Strlen (str1); leng22. = Strlen (str2); Length = Length1> leng22? Length1: leng22;  //  Store two numbers in num []     For (I = length- 1 , J = length1- 1 ; J> = 0 ; I --, j -- ) {Num1 [I] = Str1 [J]- '  0  '  ;}  For (I = length- 1 , J = leng22- 1 ; J> = 0 ; I --, j --) {Num2 [I] = Str2 [J]- '  0  '  ;}  //  Subtraction from the back to the back      For (I = length- 1 ; I> = 0 ; I -- ) {Dvalue [I] = Flag + num1 [I]- Num2 [I];  If (Dvalue [I] < 0 ) {Dvalue [I] = Dvalue [I] + 10  ; Flag =- 1 ; //  Indicates the borrow position  }  Else  {Flag = 0  ;}}  //  If the above loop is exceeded, flag =-1 indicates that the difference is negative.  // When the result is negative, the subsequent algorithm example is as follows:  //  For example, after the bitwise calculation, the difference value is 123, and the actual difference value is 1123-456.  //  Then, the difference between 667 and 1000 is the actual difference. Set a negative flag to neg_flag, and then use 1000-667.  //  That is, use 10 minus the second bit, and then use 9 minus the rest.      If (Flag =- 1  ) {Neg_flag = 1  ; Dvalue [Length - 1 ] = 10 -Dvalue [length- 1  ];  For (I = length- 2 ; I> = 0 ; I -- ) {Dvalue [I] = 9 - Dvalue [I] ;}}  //  Skip the leading zero before outputting the difference value I = 0  ;  While (Dvalue [I] =0 & (I < Length) {I ++ ;}  //  If the two numbers are equal, all the difference values are 0 and only one 0 is output.      If (I = Length) {putchar (  '  0  '  );  Return   0  ;}  // If it is a negative number, the negative number is output first.      If (Neg_flag = 1  ) {Putchar (  '  -  '  );}  For (; I <length; I ++ ) {Printf (  "  % D  "  , Dvalue [I]);}  Return   0 ;}