如何实现"appendFile"功能？

Question

我可以使用以下函数来覆盖文本文件:

let writeFile ~filename:fn s =
let oc = open_out fn in
    output_string oc s;
    close_out oc ;;

但是,我不知道如何在文本文件中附加一行？

Answer 1

您可以将附加模式标志传递Open_append给open_out_gen函数:

let _ =
    let oc = open_out_gen [Open_creat; Open_text; Open_append] 0o640 "a.txt" in
    output_string oc "append\n";
    close_out oc