TextOut() - "invalid null pointer"

TextOut() - "invalid null pointer"

By : Ben Lambert
Date : November 17 2020, 11:55 AM
seems to work fine You are telling TextOut that the length of the string is 500 characters when it is really only 15 characters. Since TextOut does not stop at a null terminator it will draw exactly how many characters you tell it to. The extra text, garbage, and Chinese characters you are seeing is other data that is stored after the string literal "This is a test.".
code :

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What does "GLib-GObject-WARNING **: instance with invalid (NULL) class pointer" mean?

What does "GLib-GObject-WARNING **: instance with invalid (NULL) class pointer" mean?

By : ijliao
Date : March 29 2020, 07:55 AM
I wish this helpful for you Something's pretty messed-up.
g_set_prgname() is an internal routine that's normally only called by a program initializer like gdk_init() or gtk_init() (which calls gdk_init()). So if it's being called twice, well, it shouldn't. I read your answer, and perhaps some Glade initialization routine is calling it redundantly. It would help to know what versions of Glade and GTK you're running.
How does one avoid "invalid memory address or null pointer dereference" errors?

How does one avoid "invalid memory address or null pointer dereference" errors?

By : user4196764
Date : March 29 2020, 07:55 AM
will help you In this particular case, you could use idiomatic Go. Change AStructList *[]Astruct to AStructList []*Astruct. For example,
code :
package main

import "fmt"

type Astruct struct {
    Number int
    Letter string

type Bstruct struct {
    foo         int
    AStructList []*Astruct

type Cstruct struct {

func (a *Astruct) String() string {
    return fmt.Sprintf("Number = %d, Letter = %s", a.Number, a.Letter)

func main() {
    astructlist := make([]*Astruct, 3)            // line 1
    for i := range astructlist {                  // line 2
        astructlist[i] = &Astruct{i, "a"}         // line 3 
    }                                             // line 4
    c := new(Cstruct)
    c.Bstruct = Bstruct{100, astructlist}         // line 6

    for _, x := range c.Bstruct.AStructList {
        fmt.Printf("%s\n", x)
why comparing null function pointer results in "invalid operands to binary =="

why comparing null function pointer results in "invalid operands to binary =="

By : pp_Michael
Date : March 29 2020, 07:55 AM
around this issue Can somebody please explain to me why the below code got the "invalid operands to binary ==" error? , And you should refer to the correct member in the struct:
code :
if (table[0].func == NO_FUNC)
I am getting the error "invalid null pointer"

I am getting the error "invalid null pointer"

By : Deeksha Prasad
Date : March 29 2020, 07:55 AM
like below fixes the issue I want to read in student names from a file and insert them into my linked-list, but I am having this problem with an error box. The error reads "Expression: Invalid Null Pointer." , I found my problem.
code :
    this -> head = new Node(0);
    mySize = 0;
    string data = "";

LList::Node::Node (string data_value)
    this -> data = data_value;
    this -> next = NULL;
Are pointers to allocated memory outside object's lifetime "invalid pointer[s]" or "pointer[s] to an obje

Are pointers to allocated memory outside object's lifetime "invalid pointer[s]" or "pointer[s] to an obje

By : user3334091
Date : March 29 2020, 07:55 AM
wish helps you
To which of these categories belong pointers to allocated memory outside the lifetime of objects, specifically the values of a at // (1) through // (3) and b at // (4) in the following program?
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