// 这是原始阶段， 我的第一想法；

#include <iostream.h>

#include <fstream.h>

#include <cmath>

void writefile(char* str)

{

ofstream out1;

out1.open("modi2.txt", ios::binary|ios::app);

for (int i = 0; str[i] != 0; i++)

{

out1.put(str[i]);

}

out1.close();

}

void fun(int x)

{

cout<<"请输入一个整数：";

cin>>x;

int a[1024];

int i = 0;

while (x > 0)

{

a[i++] = x % 2;

x = x / 2;

}

int len = i;

char b[1024];

for (int j = 0; j < len; j++, i--)

{

b[j] = a[i-1] + '0';

cout<<b[j];

}

b[j] = 0;

writefile(b);

}

void clearfile()

{

ofstream out1;

out1.open("modi2.txt");

out1.close();

}

int main()

{

clearfile();

fun(13);

return 0;

}

// 下面程序显示了指针的妙用。

char str[32];

int i;

for (i = 30; i >= 0; i--)

{

if (x % 2)

str[i] = '1'; // str[i] = (x%2) + '0';

else

str[i] = '0';

x = x / 2;

if (!x)

break;

}

str[31] = '\0';

cout<<&str[i]<<endl;

writefile(&str[i]);