Print a signed 64-bit integer in hexadecimal and octal

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I'm creating a program that prints a signed 64-bit variable in hexadecimal and octal format. I searched online for the format specifier, but I only found results for unsigned 64-bit integers.

c
1 Answers

Specifiers %o and %x indeed are defined for unsigned integral values only. In case of a signed input, and if you want to show a signed value like -234 with a "sign" in hex as well, e.g. -ea, you'll have to handle signed values separately. Otherwise, if you want a negative value to show up as the proper unsigned conversion (i.e. the two's complement representation), simply cast it to unsigned:

int main() {

    int input = -234;
    if (input < 0) {
       printf("-%x\n", (unsigned)(-input));
    } else {
       printf("%x\n", (unsigned)input);
    }
    
    printf("%x\n", (unsigned)input);
}

Output:

-ea
ffffff16
user_26300320
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