为什么我的浮点值不能正确打印？

Question

I am trying to print out the floating point values 0x40a00000 and 0xc0200000. But the values that I print out and the correct values according to the IEEE-754 Floating Point Converter (https://www.h-schmidt.net/FloatConverter/IEEE754.html) are completely different:

The values I should get according to the IEEE converter:

0x3F800000 = 5.00
0xBF000000 = -2.50

The values I get when running:

float tmp1 = 0x40a00000;
float tmp2 = 0xc0200000;

printf("tmp1 = %.2f\n", tmp1);
printf("tmp2 = %.2f\n", tmp2);

is

tmp1 = 1084227584.00
tmp2 = 3223322624.00

For some reason my C code isn't formatting the bits of the floating point values according to IEEE standards and is instead formatting them as if it were an int with a decimal point

Answer 1

These are assigning the float representation of the hexadecimal numbers to the floats.

Instead, do this:

int i1 = 0x40a00000;
int i2 = 0xc0200000;
float tmp1, tmp2;
memcpy(&tmp1, &i1, sizeof(int));
memcpy(&tmp2, &i2, sizeof(int));

Print them:

printf("tmp1 = %.2f\n", tmp1);
printf("tmp2 = %.2f\n", tmp2);

Output:

tmp1 = 5.00
tmp2 = -2.50

Full example:

#include <stdio.h>
#include <string.h>

int main(void)
{
    int i1 = 0x40a00000;
    int i2 = 0xc0200000;
    float tmp1, tmp2;
    memcpy(&tmp1, &i1, sizeof(int));
    memcpy(&tmp2, &i2, sizeof(int));
    printf("tmp1 = %.2f\n", tmp1);
    printf("tmp2 = %.2f\n", tmp2);
}