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#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#define LONGMIN 0x8000000000000000
#define RED "\x1b[91m"
#define GRN "\x1b[92m"
#define RST "\x1b[0m"
/* 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;
}
void handle_main_arg(int argc, char *argv[]) {
long number;
char *bin;
int i;
/* Iterate over every argument and print conversions to stdout */
for (i = 1; i < argc; ++i) {
number = atol(argv[i]);
/* 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 == LONGMIN) {
fprintf(stderr, RED "Error: " RST "The number %li does not fit in 64 bits\n", number);
continue;
}
bin = tobin(number);
printf("Binary for %-20li: %s\n", number, bin);
free(bin);
}
}
int handle_main_noarg(char *filename) {
FILE *f;
long num, pos, max;
char *buf;
f = fopen(filename, "r+");
if (!f) {
fprintf(stderr, RED "Error: could not open file %s" RST " (errno %i: %s)\n", filename, errno, strerror(errno));
return EXIT_FAILURE;
}
fseek(f, 0, SEEK_END);
max = ftell(f);
fseek(f, 0, SEEK_SET);
while (fscanf(f, "%li", &num) == 1) {
if (num == LONGMIN) {
fprintf(stderr, RED "Error: " RST "The number %li does not fit in 64 bits\n", num);
continue;
}
pos = ftell(f); /* Remember position in file */
if (pos >= max) break;
fseek(f, 0, SEEK_END); /* Go to end of file */
buf = tobin(num); /* Perform conversion */
fprintf(f, "%s\n", buf); /* Write the conversion there */
fseek(f, pos, SEEK_SET); /* Restore file position*/
free(buf);
}
fclose(f);
return EXIT_SUCCESS;
}
int main(int argc, char* argv[]) {
char * filename;
if (argc < 2) {
fprintf(stderr, RED "Error: Invalid arguments.\n" RST "Usage: " GRN "%s filename" RST " or " GRN "%s num1 num2 num3...\n" RST, *argv, *argv);
return EXIT_FAILURE;
}
if (argc == 2) return handle_main_noarg(argv[1]);
handle_main_arg(argc, argv);
return EXIT_SUCCESS;
}
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