string-format: String.format/formatted/printf cheat sheet module (specifier anatomy, rounding vs C printf, locales, Indian lakh/crore grouping Formatter cannot do, format exceptions, %t dates, concat cost), 11 contract tests

Co-Authored-By: Claude Sonnet 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_017ic4b7Sr2zcoRD2watXv1G

string-format/scripts/printf_compare.c

@@ -0,0 +1,9 @@
+/* The same four values RoundingDemo formats, through C's printf, for comparison with Java's %f. */
+#include <stdio.h>
+int main(void) {
+    printf("C printf   %%.2f of 2.675 : %.2f\n", 2.675);
+    printf("C printf   %%.1f of 0.35  : %.1f\n", 0.35);
+    printf("C printf   %%.2f of 1.005 : %.2f\n", 1.005);
+    printf("C printf   %%.2f of 0.125 : %.2f\n", 0.125);
+    return 0;
+}