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#include<stdlib.h>
#include<stdio.h>
#define RED "\x1b[91m"
#define GRN "\x1b[92m"
#define RST "\x1b[0m"
/* breaks (segfaults) if x = 0x8000000000000000 */
char* tobin(long int x) {
size_t i = 0, j = 0;
char buffer[64];
char *ret;
char sgn = x < 0;
x *= ((x > 0) << 1) - 1; /* Negate the number without if statement */
for (; x; x >>= 1) buffer[i++] = '0' + (x & 1); /* Write the bits to the buffer */
ret = calloc(i + 1 + sgn, sizeof *ret); /* Allocate an arary for the number */
ret[0] = '-'; /* Always write minus as the first sign*/
j += sgn; /* If sign is negative, increment j so that '-' is not overwritten */
while (i) ret[j++] = buffer[--i]; /* reverse copy buffer into ret */
return ret;
}
int main(int argc, char* argv[]) {
long number;
char *bin;
if (argc != 2) {
fprintf(stderr, RED "Error: Invalid amount of arguments\n" RST "Usage: " GRN "%s <number>\n" RST , argv[0]);
return EXIT_FAILURE;
}
number = atol(argv[1]);
/* Since I am negating a number using the branchless trick,
* Multiplying this number by -1 still gives you a negative number because of the overflow
* Unfortunately this has to be handled separately */
if (number == 0x8000000000000000) {
puts(RED "Error: " RST "The number does not fit in 64 bits");
return EXIT_FAILURE;
}
bin = tobin(number);
printf("Binary for %-20li: %s\n", number, bin);
free(bin);
return EXIT_SUCCESS;
}
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