1 files changed, 113 insertions, 0 deletions
diff --git a/temp.c b/temp.c
new file mode 100644
index 0000000..56bbe74
--- /dev/null
+++ b/temp.c
@@ -0,0 +1,113 @@
+#include <u.h>
+#include <libc.h>
+
+enum {
+	C,	/* celsius */
+	F,	/* fahrenheit */
+	K	/* kelvin */
+};
+
+int iscale = F;
+int oscale = C;
+
+double
+c2f(double T)
+{
+	return T * 9/5 + 32;
+}
+
+double
+c2k(double T)
+{
+	return T + 273.15;	
+}
+
+double
+f2c(double T)
+{
+	return (T-32) * 5/9;
+}
+
+double
+f2k(double T)
+{
+	return c2k(f2c(T));
+}
+
+double
+k2c(double T)
+{
+	return T - 273.15;
+}
+
+double
+k2f(double T)
+{
+	return c2f(k2c(T));
+}
+
+double
+ident(double T)
+{
+	return T;
+}
+
+double (*convtab[3][3])(double) = {
+ [C][C] ident,
+ [C][F] c2f,
+ [C][K] c2k,
+ [F][C] f2c,
+ [F][F] ident,
+ [F][K] f2k,
+ [K][C] k2c,
+ [K][F] k2f,
+ [K][K] ident
+};
+
+int
+getscale(char c)
+{
+	switch(c){
+	case 'C': return C;
+	case 'F': return F;
+	case 'K': return K;
+	}
+	return -1;
+}
+
+void
+usage(void)
+{
+	fprint(2, "usage: %s [-i scale] [-o scale] temp\n", argv0);
+	exits("usage");
+}
+
+void
+main(int argc, char *argv[])
+{
+	char *s;
+	double iT, oT;
+
+	ARGBEGIN{
+	case 'i':
+		s = EARGF(usage());
+		iscale = getscale(*s);
+		if(iscale < 0)
+			sysfatal("uknown input scale");
+		break;
+	case 'o':
+		s = EARGF(usage());
+		oscale = getscale(*s);
+		if(oscale < 0)
+			sysfatal("uknown output scale");
+		break;
+	default: usage();
+	}ARGEND;
+
+	if(argc < 1)
+		usage();
+	iT = strtod(*argv, nil);
+	oT = (*convtab[iscale][oscale])(iT);
+	print("%g\n", oT);
+	exits(0);
+}