|
|
|
This thread is locked; no one can reply to it.
|
| Differences betwen al_ustr_new and al_ustr_new() |
|
AMCerasoli
Member #11,955
May 2010
 |
Hi there!. Who is kind enough to give me an explanation about the differences between al_ustr_new_from_buffer() and al_ustr_new(). Obviously a technical explanation, since have just save me a lot of trouble, I was getting a lot of garbage from one of my char pointers when reading from file an using the al_ustr_new_from_buffer() function the problem have just disappeared... It's like eliminates the garbage automatically. But that garbage seems to be created by the al_fread function. Thanks. PS: I know I could search in the source, but I doubt I could understand something... DAMN!! THE TITTLE! fuck!
|
|
Matthew Leverton
Supreme Loser
January 1999
 |
al_ustr_new(s) is the same thing as al_ustr_new_from_buffer(s, strlen(s)). |
|
AMCerasoli
Member #11,955
May 2010
|
Well... On my system they don't return the same result. al_ustr_new() gives me a lot of garbage and al_ustr_new_from_buffer() works fine, this is the smaller example I could come up with. Probable I'm doing something wrong. Check out the console, not the allegro window. 1#include <iostream>
2#include <allegro5/allegro.h>
3#include <allegro5/allegro_font.h>
4#include <allegro5/allegro_ttf.h>
5
6class OPC_DATA{
7
8 public:
9
10 bool modalidad_normal;
11 bool catg0, catg1, catg2, catg3, catg4;
12 ALLEGRO_USTR* URL_page;
13 float sfx, music;
14 bool fullscreen;
15 int len;
16
17
18 OPC_DATA() {
19
20 ALLEGRO_FILE* file = al_fopen("datos.dat", "rb");
21
22 if(file){ ///Si el archivo existe...
23
24 modalidad_normal = al_fread32be(file);
25 catg0 = al_fread32be(file);
26 catg1 = al_fread32be(file);
27 catg2 = al_fread32be(file);
28 catg3 = al_fread32be(file);
29 catg4 = al_fread32be(file);
30 len = al_fread32be(file);
31
32 std::cout<<"len: "<<len<<std::endl;
33 if(len==5)Beep(600,20);
34
35 char *buf = new char [len];
36 al_fread(file, buf, len);
37
38 if(len==0) // This is because if the len==0 the URL_page variable is filled with garbage
39 URL_page = al_ustr_new("");
40 else
41 ///Here!! <<<---- Change the functions a see the difference.
42 /// remember to delete the datos.dat file after changing the function
43 //URL_page = al_ustr_new(buf); //This is bad
44 URL_page = al_ustr_new_from_buffer(buf, len); // This is good
45
46 delete [] buf;
47
48 int T_sfx = al_fread32be(file);
49 sfx = *reinterpret_cast<float*>(&T_sfx);
50
51 int T_music = al_fread32be(file);
52 music = *reinterpret_cast<float*>(&T_music);
53
54 fullscreen = al_fread32be(file);
55
56 al_fclose(file);
57 //Beep(800,200);
58
59 }else{ /// Si el archivo NO existe...
60
61 modalidad_normal = true;
62 catg0 = true;
63 catg1 = true;
64 catg2 = true;
65 catg3 = true;
66 catg4 = true;
67 URL_page = al_ustr_new("");
68 sfx = 1.6;
69 music = 1.5;
70 fullscreen = false;
71
72 al_fclose(file);
73 }
74
75 }
76
77 ~OPC_DATA() {
78
79 ALLEGRO_FILE* file = al_fopen("datos.dat", "wb");
80
81 al_fwrite32be(file, modalidad_normal);
82 al_fwrite32be(file, catg0);
83 al_fwrite32be(file, catg1);
84 al_fwrite32be(file, catg2);
85 al_fwrite32be(file, catg3);
86 al_fwrite32be(file, catg4);
87
88 al_fwrite32be(file, (int)al_ustr_size(URL_page));
89 al_fwrite(file, al_cstr(URL_page), al_ustr_size(URL_page));
90
91 al_fwrite32be(file, *reinterpret_cast<int*>(&sfx));
92 al_fwrite32be(file, *reinterpret_cast<int*>(&music));
93 al_fwrite32be(file, fullscreen);
94
95 al_fclose(file);
96 al_ustr_free(URL_page);
97
98 }
99
100};
101
102int main()
103{
104 al_init();
105
106 al_init_font_addon(); // initialize the font addon
107 al_init_ttf_addon();// initialize the ttf (True Type Font) addon
108 ALLEGRO_FONT *font = al_load_ttf_font("consola.ttf",72,0 ); // load the font | Font from Larabie Free Fonts
109 ALLEGRO_DISPLAY *display = NULL;
110 display = al_create_display(640,480);
111
112// Closing and opening simulation
113
114 for (int i=0;i<5;i++){
115 OPC_DATA *od = new OPC_DATA;
116 al_ustr_append_chr(od->URL_page, 97); // This adds the letter "a"
117 delete od;
118 }
119// - - - - - - - - - - - - - - - -
120
121 OPC_DATA *od1 = new OPC_DATA;
122 al_ustr_append_chr(od1->URL_page, 97);
123
124 al_clear_to_color(al_map_rgb(50,10,70));
125 al_draw_ustr(font, al_map_rgb(255,255,255), 640/2, (480/4),ALLEGRO_ALIGN_CENTRE, od1->URL_page);
126
127 al_flip_display();
128
129 std::cout<<al_cstr(od1->URL_page);
130 al_rest(0.9);
131
132 al_destroy_display(display);
133 delete od1;
134
135 return 0;
136}
|
|
SiegeLord
Member #7,827
October 2006
 |
Well, as Matthew said, al_ustr_new uses strlen which computes the length of the string by looking for the first 0 character in that memory block. I'd guess that you don't write the trailing 0 when you save the .dat file, so strlen reports something much larger than what it should be. "For in much wisdom is much grief: and he that increases knowledge increases sorrow."-Ecclesiastes 1:18 |
|
Matthew Leverton
Supreme Loser
January 1999
|
Change it to: char *buf = new char [len + 1]; buf[len] = 0; You must null terminate each of your strings. (Or you can use al_ustr_new_from_buffer() for every case.) |
|
SiegeLord
Member #7,827
October 2006
|
And al_ustr_size doesn't include the trailing 0. Just use the al_ustr_new_from_buffer and be done with it. EDIT: Nvm, can't read. "For in much wisdom is much grief: and he that increases knowledge increases sorrow."-Ecclesiastes 1:18 |
|
Matthew Leverton
Supreme Loser
January 1999
|
SiegeLord said: That won't help though since he does this (confirming my guess): I'm talking about when he loads the strings. But I'd use al_ustr_new_from_buffer() since it exists for this purpose. |
|
AMCerasoli
Member #11,955
May 2010
|
Hmm, I get it now, I didn't know that al_ustr_new() was looking for the null character, but otherwise how would know when to stop?. Yhea the best choice is to keep using al_ustr_new_from_buffer() since I'm already saving a flag into the file, otherwise I could save the string with the null character included, and read the file until I find that null charter and then move on with the rest, and I wouldn't need the len flag.
|
|
|
