## IupSetAttribute

Sets an interface element attribute. See also the Attributes Guide section.

### Parameters/Return

    void IupSetAttribute(Ihandle *ih, const char *name, const char *value); [in C]
    void IupSetStrAttribute(Ihandle *ih, const char *name, const char *value); [in C]
    iup.SetAttribute(ih: ihandle, name: string, value: any) [in Lua]

    void IupSetAttributeId(Ihandle *ih, const char *name, int id, const char *value); [in C]
    void IupSetStrAttributeId(Ihandle *ih, const char *name, int id, const char *value); [in C]
    iup.SetAttributeId(ih: ihandle, name: string, id: number, value: any) [in Lua]

    void IupSetAttributeId2(Ihandle* ih, const char* name, int lin, int col, const char* value); [in C]
    void IupSetStrAttributeId2(Ihandle* ih, const char* name, int lin, int col, const char* value); [in C]
    iup.SetAttributeId2(ih: ihandle, name: string, lin, col: number, value: any) [in Lua]

ih: Identifier of the interface element. If NULL will set in the global environment.
name: name of the attribute.
id, lin, col: used when the attribute has additional ids.
value: value of the attribute. If NULL (nil in Lua), the default value will be used.

### Utility Functions

These functions can also be used to set attributes from the element:

    void IupSetStrf  (Ihandle* ih, const char* name, const char* format, ...);
    void IupSetStrfV (Ihandle* ih, const char* name, const char* format, va_list arglist);
    void IupSetInt   (Ihandle* ih, const char* name, int value);
    void IupSetFloat (Ihandle* ih, const char* name, float value);
    void IupSetDouble(Ihandle* ih, const char* name, double value);
    void IupSetRGB   (Ihandle *ih, const char* name, unsigned char r, unsigned char g, unsigned char b);
    void IupSetRGBA  (Ihandle *ih, const char* name, unsigned char r, unsigned char g, unsigned char b, unsigned char a); (since 3.29)

    void IupSetStrfId  (Ihandle *ih, const char* name, int id, const char* format, ...);
    void IupSetStrfIdV (Ihandle* ih, const char* name, int id, const char* format, va_list arglist);
    void IupSetIntId   (Ihandle* ih, const char* name, int id, int value);
    void IupSetFloatId (Ihandle* ih, const char* name, int id, float value);
    void IupSetDoubleId(Ihandle* ih, const char* name, int id, double value);
    void IupSetRGBId   (Ihandle *ih, const char* name, int id, unsigned char r, unsigned char g, unsigned char b);

    void IupSetStrfId2  (Ihandle* ih, const char* name, int lin, int col, const char* format, ...);
    void IupSetStrfId2V (Ihandle* ih, const char* name, int lin, int col, const char* format, va_list arglist);
    void IupSetIntId2   (Ihandle* ih, const char* name, int lin, int col, int value);
    void IupSetFloatId2 (Ihandle* ih, const char* name, int lin, int col, float value);
    void IupSetDoubleId2(Ihandle* ih, const char* name, int lin, int col, double value);
    void IupSetRGBId2   (Ihandle *ih, const char* name, int lin, int col, unsigned char r, unsigned char g, unsigned char b);

    [There is no equivalent in Lua]

IupSetStrf* functions (old IupSetfAttribute) uses the same format specification as the sprintf function in C. This function is very useful when several values must be combined into one string. When passing float values, it uses the format "%.9g" to maximize precision. When passing double values, it uses the format "%.18g" to maximize precision.

All the utility functions use the IupSetStrAttribute* functions internally.

### Notes

See the Attributes Guide for more details.

IupSetAttribute can store only constant strings (like "Title", "30", etc) or application pointers. The given value is not duplicated as a string, only a reference is stored. Therefore, you can store application custom attributes, such as a context structure to be used in a callback.

IupSetStrAttribute (old IupStoreAttribute) can only store strings. The given string value will be duplicated internally.

Id based attributes are always non inheritable, so all IupSet*Id functions will not propagate the attribute to the children. Ids are usually non negative values (id >= 0), with a few exceptions.

### Examples

A very common mistake when using IupSetAttribute is to use local string arrays to set attributes. For ex:

    char value[30];
    sprintf(value, "CODE - %d", i);
    IupSetAttribute(dlg, "BADEXAMPLE", value)  // WRONG  (value pointer will be internally stored,
                                               //         but its memory will be released at the end of this scope)
                                               // a common bad practice is to declare value as static
                                               // Use IupSetStrAttribute in this case

    char *value = malloc(30);
    sprintf(value, "%d", i);
    IupSetAttribute(dlg, "EXAMPLE", value)     // correct  (but to avoid memory leaks you should free the pointer
                                                            after the dialog has been destroyed)

    IupSetAttribute(dlg, "VISIBLE", "YES")     // correct (constant values still exists after this scope)
    IupSetAttribute(text, "VALUE", "Hello!");
    IupSetAttribute(indicator, "VALUE", "ON");

    char attrib[30];
    sprintf(attrib, "MY ITEM (%d)", i);
    IupSetAttribute(dlg, attrib, "Test")       // correct (attribute names are always internally duplicated)

    struct{
      int x;
      int y;
    } myData;

    IupSetAttribute(text, "myData", (char*)&myData);  // WRONG, will work only if myData is a global variable.

    struct myData* mydata = malloc(sizeof(struct myData));
    IupSetAttribute(dlg, "MYDATA", (char*)mydata);    // correct (unknown attributes will be stored as pointers)

Defines a radio’s initial value:

    Ihandle *portrait = IupToggle("Portrait" , NULL);
    Ihandle *landscape = IupToggle("landscape" , NULL);
    Ihandle *box = IupVbox(portrait, IupFill(),landscape, NULL);
    Ihandle *mode = IupRadio(box);
    IupSetHandle("landscape", landscape); /* associates a name to initialize the radio */
    IupSetAttribute(mode, "VALUE", "landscape"); /* defines the radio’s initial value */

### See Also

IupGetAttribute, IupSetAttributes, IupGetAttributes, IupSetGlobal, IupGetGlobal