(Reporter) How can we improve 10 to 2? (C/C ++) (C) (STL)

Abstract
Printf () can only display the value of the 10, 8, and 16 bits, but cannot display the value of the 2 bits, but sometimes we want to directly display the 2-in-number.

Introduction
Use environment: Visual C ++ 8.0/Visual Studio 2005

Method 1:
This is changed from C primer plus 5/E. Bit operations are used to bring 10 in two places, which is a pretty good method.

Decimal2binary. C/C

1 /*  
2 (C) oomusou 2008 Http://oomusou.cnblogs.com
3
4 Filename: decimal2binary. c
5 Compiler: Visual C + + 8.0
6 Description: Demo how to convert deciaml to binary by C
7 Release: 07/22/2008 1.0
8 */
9 # Include < Stdio. h >
10
11 Char * Itobs ( Int N, Char   * PS ){
12 Int Size =   8   *   Sizeof (N );
13 Int I = Size - 1 ;
14
15 While (I + 1 ){
16 PS [I -- ] = ( 1   & N) +   ' 0 ' ;
17 N >>=   1 ;
18 }
19
20 PS [size] =   ' \ 0 ' ;
21 Return PS;
22 }
23
24 Int Main (){
25 Int N =   8 ;
26 Char S [ 8   *   Sizeof (N) +   1 ];
27
28 Printf ( " % D = % s \ n " , N, itobs (N, S ));
29 }

Results

8   =   00000000000000000000000000001000

16 rows

PS [I -- ] = ( 1   & N) +   ' 0 ' ;

Perform mask on N and retrieve 0th bits. This sort method is faster than % 2. Because it is an int, it is converted into char through + '0, the delimiter column of the stored string.

17 rows

N >>=   1 ;

0 bit processing, processing 1 bit.

15 rows

While (I + 1 ){

Equivalent to while (I> = 0)

20 rows

PS [size] =   ' \ 0 ' ;

End the string.

Method 2:
If you can use C ++, there will be a very simple solution.

Decimal2binary. CPP/C ++

1 /*  
2 (C) oomusou 2008 Http://oomusou.cnblogs.com
3
4 Filename: decimal2binary. cpp
5 Compiler: Visual C + + 8.0
6 Description: Demo how to convert deciaml to binary by C ++
7 Release: 07/22/2008 1.0
8 */
9 # Include < Iostream >
10 # Include < Bitset >
11
12 Using   Namespace STD;
13
14 Int Main (){
15 Int N =   8 ;
16 Bitset < Sizeof (N) *   8 > S (n );
17
18 Cout < N <   " = "   < S < Endl;
19 }

Results

8   =   00000000000000000000000000001000

After bitset is used, cout comes out as 2.

Conclusion
Another method is to use % 2 in combination with memory loss. However, since the bit loss method is fast and saves the attention, there is not much discussion.

Reference
Stephen Prata, C primer plus 5/E