在C语言中，浮点数的二进制输出可通过以下两种方式实现：

一、直接输出二进制表示（使用 `%a` 格式说明符）

C99标准引入了 `%a` 格式说明符，支持以二进制形式输出浮点数。示例如下：

```c

include

int main() {

float num = 3.14;

printf("二进制形式: %an", num); // 输出类似 1.0011001100110011e+00

return 0;

}

```

二、手动转换并输出二进制字符串

整数部分转换

通过不断除以2取余数，将整数部分转换为二进制字符串，最后反转结果。例如：

```c

include

include

void intToBinary(unsigned long n, char *binary) {

int r;

int index = 0;

while (n >

0) {

r = n % 2;

binary[index++] = (r ? '1' : '0');

n /= 2;

}

binary[index] = '0';

// 反转字符串

for (int i = 0; i < index / 2; i++) {

char temp = binary[i];

binary[i] = binary[index - i - 1];

binary[index - i - 1] = temp;

}

}

int main() {

unsigned long num = 9;

char binary = {0}; // 32位整数 + 1个结束符

intToBinary(num, binary);

printf("二进制形式: %sn", binary); // 输出 00000000 00000000 00000000 00001001

return 0;

}

```

小数部分转换

通过不断乘以2取整，将小数部分转换为二进制字符串，直到达到指定精度或结果为0。例如：

```c

include

include

void floatToBinary(float num, char *binary, int precision) {

int i = 0;

while (precision >

0) {

float temp = num * 2;

int bit = (temp >

= 1) ? 1 : 0;

binary[i++] = bit + '0';

num -= bit;

precision--;

}

binary[i] = '0';

}

int main() {

float num = 0.2;

char binary = {0};

floatToBinary(num, binary, 20);

printf("二进制形式: 0.0011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001