<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/loose.dtd"> <HTML ><HEAD ><TITLE >How do I validate/limit/filter the input to a GtkEntry? [GTK 2.x]</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.79"><LINK REL="HOME" TITLE="GTK+ FAQ" HREF="book1.html"><LINK REL="UP" TITLE="Development with GTK+: widget specific questions" HREF="c698.html"><LINK REL="PREVIOUS" TITLE="How do I make a GtkEntry widget activate on pressing the Return key?" HREF="x829.html"><LINK REL="NEXT" TITLE="How do I use horizontal scrollbars with a GtkText widget?" HREF="x838.html"></HEAD ><BODY CLASS="SECT1" BGCOLOR="#FFFFFF" TEXT="#000000" LINK="#0000FF" VLINK="#840084" ALINK="#0000FF" ><DIV CLASS="NAVHEADER" ><TABLE SUMMARY="Header navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="3" ALIGN="center" >GTK+ FAQ</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="bottom" ><A HREF="x829.html" ACCESSKEY="P" ><<< Previous</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" >Development with GTK+: widget specific questions</TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="x838.html" ACCESSKEY="N" >Next >>></A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><DIV CLASS="SECT1" ><H1 CLASS="SECT1" ><A NAME="AEN833" >How do I validate/limit/filter the input to a GtkEntry? <I CLASS="EMPHASIS" >[GTK 2.x]</I ></A ></H1 ><P >If you want to validate the text that a user enters into a GtkEntry widget you can attach to the "insert_text" signal of the entry, and modify the text within the callback function. The example below forces all characters to uppercase, and limits the range of characters to A-Z. Note that the entry is cast to an object of type GtkEditable, from which GtkEntry is derived.</P ><TABLE BORDER="0" BGCOLOR="#E0E0E0" WIDTH="100%" ><TR ><TD ><PRE CLASS="PROGRAMLISTING" >#include <ctype.h> #include <gtk/gtk.h> void insert_text_handler (GtkEntry *entry, const gchar *text, gint length, gint *position, gpointer data) { GtkEditable *editable = GTK_EDITABLE(entry); int i, count=0; gchar *result = g_new (gchar, length); for (i=0; i < length; i++) { if (!isalpha(text[i])) continue; result[count++] = islower(text[i]) ? toupper(text[i]) : text[i]; } if (count > 0) { g_signal_handlers_block_by_func (G_OBJECT (editable), G_CALLBACK (insert_text_handler), data); gtk_editable_insert_text (editable, result, count, position); g_signal_handlers_unblock_by_func (G_OBJECT (editable), G_CALLBACK (insert_text_handler), data); } g_signal_stop_emission_by_name (G_OBJECT (editable), "insert_text"); g_free (result); } int main (int argc, char *argv[]) { GtkWidget *window; GtkWidget *entry; gtk_init (&argc, &argv); /* create a new window */ window = gtk_window_new(GTK_WINDOW_TOPLEVEL); gtk_window_set_title(GTK_WINDOW (window), "GTK Entry"); g_signal_connect (G_OBJECT (window), "destroy", G_CALLBACK (gtk_main_quit), NULL); entry = gtk_entry_new(); g_signal_connect(G_OBJECT(entry), "insert_text", G_CALLBACK(insert_text_handler), NULL); gtk_container_add(GTK_CONTAINER (window), entry); gtk_widget_show(entry); gtk_widget_show(window); gtk_main(); return(0); }</PRE ></TD ></TR ></TABLE ></DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE SUMMARY="Footer navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="x829.html" ACCESSKEY="P" ><<< Previous</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="book1.html" ACCESSKEY="H" >Home</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="x838.html" ACCESSKEY="N" >Next >>></A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >How do I make a GtkEntry widget activate on pressing the Return key?</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="c698.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >How do I use horizontal scrollbars with a GtkText widget?</TD ></TR ></TABLE ></DIV ></BODY ></HTML >