diff --git a/c-basic/foo.c b/c-basic/foo.c
new file mode 100644
index 0000000..254a67a
--- /dev/null
+++ b/c-basic/foo.c
@@ -0,0 +1,22 @@
+#include <stdio.h>
+
+int foo()
+{
+  printf("I am foo\n");
+}
+
+int main()
+{
+  foo();
+}
+
+/**
+   In the written book it is foo() and main() and it returns this warning
+   ~/Projects/hwpplayer1/c-course/c-basic $ gcc foo.c 
+foo.c:3:1: warning: return type defaults to ‘int’ [-Wimplicit-int]
+    3 | foo()
+      | ^~~
+foo.c:8:1: warning: return type defaults to ‘int’ [-Wimplicit-int]
+    8 | main()
+      | ^~~~
+ **/