Handle infinity and NaN in printf

tests/stdio/printf.c

@@ -1,4 +1,5 @@
 #include <stdio.h>
+#include <math.h> // INFINITY, NAN constants
 
 int main(void) {
     int sofar = 0;
@@ -61,4 +62,16 @@ int main(void) {
     printf("%G\n", 0.0001);
     printf("%G\n", 0.00001);
     printf("%E\n", 0.00001);
+
+    double nonfinites[] = {INFINITY, -INFINITY, NAN, -NAN};
+    char *float_formats[] = {"%e", "%E", "%f", "%F", "%g", "%G"};
+    puts("\nNon-finite float madness:");
+    for (size_t i = 0; i < sizeof(float_formats)/sizeof(char *); i++) {
+        printf("%s:", float_formats[i]);
+        for (size_t j = 0; j < sizeof(nonfinites)/sizeof(double); j++) {
+            printf(" ");
+            printf(float_formats[i], nonfinites[j]);
+        }
+        printf("\n");
+    }
 }