Multiplication between large numbers-Calculation of large numbers

A few days ago, my friend encountered a big number computing problem and I wrote it in a hurry.

To tell the truth, the Code is not very well written. It is a bit messy. Post it first, and then modify it in a few days.

 

Such as calculation: 9999999999999*1234567890123

1. Package test;
3. Public class bignumber {
5. Public static double [] d1 = {9, 9, 9, 9, 9, 9, 9 };
7. Public static double [] D2 = {1, 2, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3 };
9. Public static int [] calculate (double [] D1, double [] D2 ){
11. Int result_length = 0;
13. Int result_num = 0;
15. Double [] d1_temp = NULL;
17. Double [] d2_temp = NULL;
19. Int [] result_over = NULL;
21. If (d1.length = d2.length ){
23. Result_length = d1.length;
25. Result_num = result_length;
27. D1_temp = D1;
29. D2_temp = d2;
31. } Else {
33. Result_length = (d1.length> = d2.length )? D1.length: d2.length;
35. Result_num = (d1.length <= d2.length )? D1.length: d2.length;
37. D1_temp = (d1.length <= d2.length )? D1: D2;
39. D2_temp = (d1.length> = d2.length )? D1: D2;
41. }
43. Double [] [] result = new double [result_num] [result_length + 1];
45. Int temp = 0;
47. For (INT I = result_num-1; I> = 0; I --){
49. For (Int J = result_length-1; j> = 0; j --){
51. Temp + = (INT) (d1_temp [I] * d2_temp [J]);
53. Result [I] [J + 1] = TEMP % 10;
55. Temp = temp/10;
57. }
59. Result [I] [0] = temp;
61. Temp = 0;
63. }
65. Temp = 0;
67. Int flag = 0;
69. Result_over = new int [result_num + result_length];
71. Int line_flag = result_over.length-1;
73. For (int m = Result [0]. Length-1; m> = 0; m --){
75. Flag = m;
77. For (INT n = result. Length-1; n> = 0; n --){
79. If (flag <= (result [N]. Length-1 )){
81. Temp + = Result [N] [flag];
83. } Else {
85. Break;
87. }
89. Flag ++;
91. }
93. Result_over [line_flag --] = TEMP % 10;
95. Temp = temp/10;
97. If (M = 0 ){
99. If (result. length> = 2 ){
101. For (int A = result. Length-2; a> = 0; --){
103. Flag = 0;
105. Temp + = Result [a] [flag ++];
107. For (int B = A-1; B> = 0; B --){
109. If (flag <= (result [B]. Length-1 )){
111. Temp + = Result [B] [flag];
113. } Else {
115. Break;
117. }
119. Flag ++;
121. }
123. Result_over [line_flag --] = TEMP % 10;
125. Temp = temp/10;
127. }
129. }
131. }
133. }
136. Return result_over;
138. }
140. Public static void main (string [] ARGs ){
142. Int [] d_result = calculate (D1, D2 );
144. For (INT I = 0; I <d_result.length; I ++) {// output result
146. System. Out. Print ("" + d_result [I] + "");
148. }
151. }
153. }

 

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Result: 1 2 3 4 5 6 7 8 9 0 1 2 8 7 6 5 4 3 2 1 0 9 8 7 7