69 lines
1.4 KiB
C
69 lines
1.4 KiB
C
#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <libgen.h>
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double c2f(double celsius) {
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return ((9.0 / 5.0) * celsius) + 32.0;
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}
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double f2c(double fahrenheit) {
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return (5.0 / 9.0) * (fahrenheit - 32.0);
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}
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void die_usage(const char *prog, const char *msg) {
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fprintf(stderr, "Usage: %s <temp>[FC]\n", prog);
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if (msg != NULL) {
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fprintf(stderr, "%s\n", msg);
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}
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exit(EXIT_FAILURE);
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}
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int main(int argc, char * argv[]) {
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const char * prog = basename(argv[0]);
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int ret;
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char msg[255];
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double temp;
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char scale = '\0';
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const char *in_fmt = "%lf%c";
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const char *out_fmt = "%.2lf%c\n";
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const char *temp_string;
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if (argc < 2) {
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die_usage(prog, NULL);
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}
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if (((int)strlen(argv[1]) == 1) && (argv[1][0] == '-')) {
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ret = fscanf(stdin, in_fmt, &temp, &scale);
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} else {
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temp_string = argv[1];
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ret = sscanf(temp_string, in_fmt, &temp, &scale);
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}
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if ((ret == 0) || (ret == EOF)) {
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die_usage(prog, "No temperature provided!");
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}
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if (ret == 1) {
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die_usage(prog, "No scale provided!");
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}
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switch (scale) {
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case 'C':
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printf(out_fmt, c2f(temp), 'F');
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break;
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case 'F':
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printf(out_fmt, f2c(temp), 'C');
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break;
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default:
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sprintf(msg, "Unknown scale: '%c'", scale);
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die_usage(prog, msg);
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}
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exit(EXIT_SUCCESS);
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}
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