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I am trying to create a text box in GTK+3.0 (using C, in Linux) that can be read from as a double, where this double will be plugged into an equation and then returned in a different box.

So my question is: what is the best way to create a text box that can be typed into, and then how do I read it as a double?

I am currently trying to use gtk_entry_new() to initialize and - after a few intermediary steps - *gtk_entry_get_text to read.

My read line currently looks like this:

double y = (double)*gtk_entry_get_text(GTK_ENTRY(input_y));

I keep getting y as a pointer, and the *gtk_entry_get_text(...) is of format const gchar*

I believe the best way is to convert const gchar* into double, but how?

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$ man atof

NAME
   atof - convert a string to a double

SYNOPSIS
   #include <stdlib.h>

   double atof(const char *nptr);

DESCRIPTION
   The atof() function converts the initial portion of the string
   pointed to by nptr to double.  The behavior is the same as

       strtod(nptr, (char **) NULL);

   except that atof() does not detect errors.

RETURN VALUE
   The converted value.

したがって：

double y = atof(gtk_entry_get_text(GTK_ENTRY(input_y)));
于 2012-06-19T18:06:25.600 に答える