C - convert long int to signed hexadecimal string

Question

MASSIVE EDIT:

I have a long int variable that I need to convert to a signed 24-bit hexadecimal string without "0x" at the beginning. The string must be 6 characters, followed by the string delimiter '\ 0', so leading zeros must be added.

Examples: [-1 → FFFFFF] --- [1 → 000001] --- [71 → 000047]

Answer This looks like a trick:

long int number = 37;
char string[7];

snprintf (string, 7, "%lX", number);

Answer 1

Since you only need six digits, you may have to disguise yourself to make sure the number is what you need. Something like that:

sprintf(buffer, "%06lx", (unsigned long)val & 0xFFFFFFUL);

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Answer 2

sprintf. %lx , .

Answer 3

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Answer 4

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sprintf(buffer, "%06X", (int)value & 0xffffff);