用移位运算实现一个整数二进制形式的输出--简短程序分析

#include <stdio.h>

int

main ()

{

const int bits = sizeof(int)*8; //一个字节8位，算出是多少位的运算，如32,64

unsigned int mask = 1<<bits-1; //如果是32位运算，则是0x80000000;注意是bits-1

int n;

printf ("Please input an integer: ");

scanf ("%d", &n);

int i;

for ( i=0; i<bits; i++ )

{

//实现每次进行一次移位，这样输出n的每一位

printf ("%c", n&mask?'1':'0'); //运算后，如果不是0，就是1;注意是%c

mask = mask>>1;

}

printf ("\n");

return 0;

}

一下是实现上述功能的另外的微小改动的实现方式：

1.

#include<stdio.h>

int

main ()

{

const int bits = sizeof(int)*8;

unsigned int mask = 1<<bits-1;

int n;

printf ("Please input an integer: ");

scanf ("%d", &n);

int i;

for ( i=0; i<bits; i++ )

{

printf ("%c", n&mask?'1':'0');

n << 1;

}

printf ("\n");

return 0;

}

2.

#include<stdio.h>

int

main ()

{

const int bits = sizeof(int)*8;

unsigned int mask = 1<<bits-1;

int n;

printf ("Please input an integer: ");

scanf ("%d", &n);

int i;

for ( i=0; i<bits; i++ )

{

printf ("%c", n<0?'1':'0');

n << 1;

}

printf ("\n");

return 0;

}

3.

#include<stdio.h>

int

main ()

{

const int bits = sizeof(int)*8;

unsigned int mask = 1<<bits-1;

int n;

printf ("Please input an integer: ");

scanf ("%d", &n);

int i;

for ( i=0; i<bits; i++ )

{

printf ("%d", n<0);

n << 1;

}

printf ("\n");

return 0;

}