While using this function, remember to call bindtextdomain for as many domains as you want to use in your application. For example, if I have module1 and module2 as 2 separate domains in the same application, you can do the following:
bindtextdomain("module1", "//path/to/my/locale/folder");
bindtextdomain("module2", "//path/to/my/locale/folder");
textdomain("module1");
echo _("Label1"); // this call will get the message from module1
echo dgettext("module2", "Label1"); // this call will get the message from module2
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Viral Shah