double to hex string & hex string to double

Question

What I\'m trying to do is to convert a double to hex string and then back to double.

The following code does conversion double-to-hex string.

char *          


        

Answer 1

You want to use a union and avoid this bad habit:

char *d2c;

d2c = (char *) &a;

For just printing its not bad, its when you try to modify d2c and then use a is when you get into trouble. (same is true for any two variables or pointers (or arrays) sharing the same (theoretical) memory.

union
{
    double f;
    unsigned long ul;
} myun;

myun.f = a;
printf("0x%lX",myun.ul);

to go the other way (scanf is also a very dangerous function that should be avoided).

myun.ul=strtoul(string,NULL,16);
a=myun.f;