Trying and failing to use `fcloseall`.

ex24_iofunctions04.c

@@ -0,0 +1,27 @@
+#define _GNU_SOURCE
+#include <stdio.h>
+#include "dbg.h"
+
+
+int main(int argc, char *argv[])
+{
+    int rc = -1;
+    printf("This should be visible, I think.\n");
+
+    rc = fcloseall();
+    check(rc == 0, "Failed to close all io streams.");
+    printf("I've used `fcloseall`, so this should not be visible, right?\n");
+
+    rc = fflush(stdout);
+    check(rc != EOF, "Failed to flush stdout.");
+    printf("Maybe we won't see anything after I explicitly `fflush(stdout)`?\n");
+
+    rc = fclose(stdout);
+    check(rc != EOF, "Failed to explicitly close stdout.");
+    printf("This had better not show up, right?\n");
+
+    return 0;
+
+error:
+    return 1;
+}