diff --git a/c04_string/floats.c b/c04_string/floats.c
new file mode 100644
index 0000000..7ea31ce
--- /dev/null
+++ b/c04_string/floats.c
@@ -0,0 +1,19 @@
+/* floats.c - 一些浮点型修饰符的组合 */
+#include <stdio.h>
+
+int main(void)
+{
+    const double RENT = 3852.99; // const变量（只读变量，不是常量）
+
+    printf("*%f*\n", RENT);
+    printf("*%e*\n", RENT);
+    printf("*%4.2f*\n", RENT);
+    printf("*%3.1f*\n", RENT);
+    printf("*%10.3f*\n", RENT);
+    printf("*%10.3E*\n", RENT);
+    printf("*%+4.2f*\n", RENT);
+    printf("*%+10.2f*\n", RENT);
+    printf("*%010.2f*\n", RENT);
+
+    return 0;
+}
\ No newline at end of file