diff --git a/c04_string/prntval.c b/c04_string/prntval.c
new file mode 100644
index 0000000..9ea82c4
--- /dev/null
+++ b/c04_string/prntval.c
@@ -0,0 +1,13 @@
+/* prntval.c - printf()的返回值 */
+#include <stdio.h>
+
+int main(void)
+{
+    int bph2o = 212;
+    int rv;
+
+    rv = printf("%d F is water's boiling point.\n", bph2o);
+    printf("The printf() function printed %d characters.\n", rv);
+    
+    return 0;
+}
\ No newline at end of file