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This thread is locked; no one can reply to it.
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| Need help with input_feild(); |
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Doctor Cop
Member #16,833
April 2018
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I want to create a function which accepts's key presses and displays them in a rectangular box (field). here's the logic. Here's my updated version but still not working. showing signs of memory leak, Please Help! 1int input_field(int x1, int y1, int x2, int y2, ALLEGRO_COLOR colorU, float boundry, ALLEGRO_COLOR boundry_color, ALLEGRO_FONT *font, ALLEGRO_EVENT &event, ALLEGRO_EVENT_QUEUE *ev_queue)
2{
3 int x=0;
4 al_draw_filled_rounded_rectangle(x1, y1, x2, y2, 10, 10, colorU);
5 al_draw_rounded_rectangle(x1, y1, x2, y2, 10, 10, boundry_color, boundry);
6
7 if(event.mouse.x >= x1 && event.mouse.x <= x2 && event.mouse.y >= y1 && event.mouse.y <= y2 && event.mouse.button & 1 && event.type == ALLEGRO_EVENT_MOUSE_BUTTON_DOWN)
8 {
9 char* str1;
10 //int p=0;
11 while(1)
12 {
13 al_draw_text(font, al_map_rgb(0, 153, 0), x1+5+x, y1+5, 1, "|");
14 al_wait_for_event(ev_queue, &event);
15 switch(event.keyboard.keycode)
16 {
17 case 1:
18 strcat(str1, "a");
19 break;
20 case 2:
21 strcat(str1, "b");
22 break;
23 case 3:
24 strcat(str1, "c");
25 break;
26 case 4:
27 strcat(str1, "d");
28 break;
29 case 5:
30 strcat(str1, "e");
31 break;
32 case 6:
33 strcat(str1, "f");
34 break;
35 case 7:
36 strcat(str1, "g");
37 break;
38 case 8:
39 strcat(str1, "h");
40 break;
41 case 9:
42 strcat(str1, "i");
43 break;
44 case 10:
45 strcat(str1, "j");
46 break;
47 case 11:
48 strcat(str1, "k");
49 break;
50 case 12:
51 strcat(str1, "l");
52 break;
53 case 13:
54 strcat(str1, "m");
55 break;
56 case 14:
57 strcat(str1, "n");
58 break;
59 case 15:
60 strcat(str1, "o");
61 break;
62 case 16:
63 strcat(str1, "p");
64 break;
65 case 17:
66 strcat(str1, "q");
67 break;
68 case 18:
69 strcat(str1, "r");
70 break;
71 case 19:
72 strcat(str1, "s");
73 break;
74 case 20:
75 strcat(str1, "t");
76 break;
77 case 21:
78 strcat(str1, "u");
79 break;
80 case 22:
81 strcat(str1, "v");
82 break;
83 case 23:
84 strcat(str1, "w");
85 break;
86 case 24:
87 strcat(str1, "x");
88 break;
89 case 25:
90 strcat(str1, "y");
91 break;
92 case 26:
93 strcat(str1, "z");
94 break;
95 }
96 al_draw_text(font, al_map_rgb(0, 153, 0), x1+10, y1+5, 1, str1);
97 x+5;
98 //printf("%s", str1);
99 if(event.keyboard.keycode == ALLEGRO_KEY_ENTER)
100 {
101 break;
102 }
103 al_flip_display();
104
105 }
106 }
107 return 0;
108}
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Michael Weiss
Member #223
April 2000
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Instead of using keyboard.keycode try using keyboard.unichar see: http://liballeg.org/a5docs/trunk/events.html look under the ALLEGRO_EVENT_KEY_CHAR section then you wont need 26 case blocks...
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Doctor Cop
Member #16,833
April 2018
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I want help with converting char to string also or a way to draw the unichar in al_draw_text(); function, if you can help please reply.
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Mark Oates
Member #1,146
March 2001
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Doctor Cop said: converting char to string I would typically do that: #include <sstream> #include <string> char c = 'p'; std::string result; std::stringstream ss; ss << c; result = ss.str();
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Michael Weiss
Member #223
April 2000
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To convert a char to a string you could do this: int chr = 65; // "A" or int chr = 65; // "A" There are probably better ways to do this though, I'm looking forward to being corrected!
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Doctor Cop
Member #16,833
April 2018
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*Mark Oates*. I am using C so I can't use C++ strings! If there's a way to create an input field like some library for allegro5 or code for that, please share.
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Michael Weiss
Member #223
April 2000
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I implemented my own editable text field like this. Sorry its not a simple example with only the editable text field part. I had to include my function that shows the cursor position and my proc_controller Its quite a lot of stuff, but maybe there's something in there you can use... 1
2char fst[80];
3extern char m_serveraddress[256];
4
5void edit_server_name(void)
6{
7 strcpy(fst, m_serveraddress);
8 int char_count = strlen(fst);
9 int cursor_pos=0;
10 int old_cp=0;
11 int blink_count = 3;
12 int blink_counter = 0;
13 while (key[ALLEGRO_KEY_ENTER]) proc_controllers();
14 int quit = 0;
15 while (!quit)
16 {
17 int tx = SCREEN_W/2;
18 int ty = SCREEN_H/2;
19 int tw = (char_count+1)*4;
20
21 al_flip_display();
22 // clear text background
23 al_draw_filled_rectangle(tx-tw-8, ty-4-2, tx+tw+18, ty+4+3, palette_color[0]);
24
25 al_draw_text(font, palette_color[15], tx, ty-14, ALLEGRO_ALIGN_CENTER, "Set Server IP or Hostname");
26 // frame text
27 al_draw_rectangle (tx-tw-1, ty-4-1, tx+tw+6, ty+6, palette_color[15], 1);
28
29 rtextout_centre(NULL, fst, tx, ty+1, 15, 1, 0, 1);
30
31 if (blink_counter++ < blink_count) show_cursor(fst, cursor_pos, tx, ty-3, 15, 0, 0);
32 else show_cursor(fst, cursor_pos, tx, ty-3, 15, 1, 0);
33 if (blink_counter> blink_count*2) blink_counter = 0;
34
35 if (cursor_pos != old_cp)
36 {
37 show_cursor(fst, old_cp, tx, ty-3, 15, 1, 0); // erase old blinking cursor if moved
38 old_cp = cursor_pos;
39 blink_counter = 0;
40 }
41
42 al_rest(.08);
43 int k = proc_controllers();
44 if (key[ALLEGRO_KEY_RIGHT])
45 {
46 if (++cursor_pos > char_count) cursor_pos = char_count;
47 }
48 if (key[ALLEGRO_KEY_LEFT])
49 {
50 if (--cursor_pos < 0) cursor_pos = 0;
51 }
52 if ((key[ALLEGRO_KEY_DELETE]) && (cursor_pos < char_count))
53 {
54 for (int a = cursor_pos; a < char_count; a++)
55 fst[a]=fst[a+1];
56 --char_count;
57 fst[char_count] = (char)NULL; // set last to NULL
58 }
59 if ((key[ALLEGRO_KEY_BACKSPACE]) && (cursor_pos > 0))
60 {
61 cursor_pos--;
62 for (int a = cursor_pos; a < char_count; a++)
63 fst[a]=fst[a+1];
64 char_count--;
65 fst[char_count] = (char)NULL; // set last to NULL
66 }
67
68 k = Key_pressed_ASCII;
69 if ((k>31) && (k<127)) // insert if alphanumeric or return
70 {
71 // move over to make room
72 for (int a = char_count; a>=cursor_pos; a--)
73 fst[a+1]=fst[a];
74
75 // set char
76 fst[cursor_pos] = k;
77
78 // inc both
79 cursor_pos++;
80 char_count++;
81
82 fst[char_count] = (char)NULL; // set last to NULL
83 }
84 if (key[ALLEGRO_KEY_ENTER])
85 {
86 while (key[ALLEGRO_KEY_ENTER]) proc_controllers();
87 strcpy(m_serveraddress, fst);
88 quit = 1;
89 }
90
91 if (key[ALLEGRO_KEY_ESCAPE])
92 {
93 while (key[ALLEGRO_KEY_ESCAPE]) proc_controllers();
94 quit = 1;
95 }
96 }
97}
98
99
100void show_cursor(char *f, int cursor_pos, int xpos_c, int ypos, int cursor_color, int restore, int rot)
101{
102 int len = strlen(f);
103 char dt[40][120];
104 int row=0, col=0, cursor_row=0, cursor_col=0;
105 // get cursor row and column and fill dt
106 for (int a=0; a<len+1; a++)
107 {
108 if (a == cursor_pos)
109 {
110 cursor_row = row;
111 cursor_col = col;
112 }
113 if (f[a] == 13) // line break
114 {
115 row++;
116 col=0;
117 dt[row][col] = (char)NULL; // in case len = 0
118 }
119 else // regular char
120 {
121 dt[row][col] = f[a];
122 col++;
123 dt[row][col] = (char)NULL;
124 }
125 }
126
127 // make a string from the cursor text char
128 msg[0] = f[cursor_pos];
129 msg[1] = 0;
130
131 int x, y;
132 x = cursor_col*8+xpos_c - strlen(dt[cursor_row])*4;
133 y = ypos+cursor_row*8;
134
135 if (restore) // black background, text color text
136 {
137 al_draw_filled_rectangle(x, y, x+8, y+8, palette_color[0]);
138 al_draw_text(font, palette_color[cursor_color], x, y, 0, msg);
139 }
140
141 else // red background, black text
142 {
143 al_draw_filled_rectangle(x, y, x+8, y+8, palette_color[10]);
144 al_draw_text(font, palette_color[0], x, y, 0, msg);
145 }
146}
147
148
149
150int proc_events(ALLEGRO_EVENT ev, int ret)
151{
152 if (ev.type == ALLEGRO_EVENT_DISPLAY_CLOSE) fast_exit(0);
153 if (ev.type == ALLEGRO_EVENT_MOUSE_WARPED)
154 {
155 mouse_x = ev.mouse.x / les;
156 mouse_y = ev.mouse.y / les;
157 }
158 if (ev.type == ALLEGRO_EVENT_MOUSE_AXES)
159 {
160 mouse_x = ev.mouse.x / les;
161 mouse_y = ev.mouse.y / les;
162 mouse_z = ev.mouse.z / les;
163 mouse_dx = ev.mouse.dx;
164 mouse_dy = ev.mouse.dy;
165 mouse_dz = ev.mouse.dz;
166 }
167 if (ev.type == ALLEGRO_EVENT_MOUSE_BUTTON_DOWN)
168 {
169 if (ev.mouse.button == 1) mouse_b1 = 1;
170 if (ev.mouse.button == 2) mouse_b2 = 1;
171 if (ev.mouse.button == 3) mouse_b3 = 1;
172 if (ev.mouse.button == 4) mouse_b4 = 1;
173 }
174 if (ev.type == ALLEGRO_EVENT_MOUSE_BUTTON_UP)
175 {
176 if (ev.mouse.button == 1) mouse_b1 = 0;
177 if (ev.mouse.button == 2) mouse_b2 = 0;
178 if (ev.mouse.button == 3) mouse_b3 = 0;
179 if (ev.mouse.button == 4) mouse_b4 = 0;
180 }
181 if (ev.type == ALLEGRO_EVENT_KEY_DOWN)
182 {
183 int k = ev.keyboard.keycode;
184 key[k] = true;
185 ret = k;
186 }
187 if (ev.type == ALLEGRO_EVENT_KEY_UP)
188 {
189 int k = ev.keyboard.keycode;
190 key[k] = false;
191 if (k == ALLEGRO_KEY_PRINTSCREEN) key[k] = true; // special exception to make PRINTSCREEN work
192 }
193 if (ev.type == ALLEGRO_EVENT_KEY_CHAR)
194 {
195 Key_pressed_ASCII = ev.keyboard.unichar;
196 }
197 if (ev.type == ALLEGRO_EVENT_JOYSTICK_AXIS)
198 {
199 int jy = getJoystickNum(ev.joystick.id);
200 int jo = 0; // offset
201 if (jy == 0) jo = 0;
202 if (jy == 1) jo = 20;
203 int ax = ev.joystick.axis;
204 float pos = ev.joystick.pos;
205 if (ax == 0) // x axis
206 {
207 key[130+jo] = false;
208 key[131+jo] = false;
209 if (pos > 0) key[131+jo] = true;
210 if (pos < 0) key[130+jo] = true;
211 }
212 if (ax == 1) // y axis
213 {
214 key[128+jo] = false;
215 key[129+jo] = false;
216 if (pos > 0) key[129+jo] = true;
217 if (pos < 0) key[128+jo] = true;
218 }
219 }
220 if (ev.type == ALLEGRO_EVENT_JOYSTICK_BUTTON_DOWN)
221 {
222 int jy = getJoystickNum(ev.joystick.id);
223 int sc = get_scan_code_from_joystick(jy, 1, ev.joystick.button);
224 key[sc] = true;
225 }
226 if (ev.type == ALLEGRO_EVENT_JOYSTICK_BUTTON_UP)
227 {
228 int jy = getJoystickNum(ev.joystick.id);
229 int sc = get_scan_code_from_joystick(jy, 1, ev.joystick.button);
230 key[sc] = false;
231 }
232 return ret;
233}
234
235
236
237
238
239
240int proc_controllers()
241{
242 int ret = 0;
243 int done = 0;
244 int menu_timer_wait = 1;
245
246 if (key[ALLEGRO_KEY_PRINTSCREEN]) key[ALLEGRO_KEY_PRINTSCREEN] = 0; // special exception to make PRINTSCREEN work
247 Key_pressed_ASCII = 0;
248 if (!fullscreen) // detect if window was moved
249 {
250 al_get_window_position(display, &l_spx, &l_spy);
251 if ((l_spx != disp_x_curr) || (l_spy != disp_y_curr))
252 proc_screen_change(disp_w_curr, disp_h_curr, l_spx, l_spy, fullscreen);
253 }
254 while (!done)
255 {
256 done = 1; // default
257 while (!al_is_event_queue_empty(event_queue))
258 {
259 ALLEGRO_EVENT ev;
260 if (ev.type == ALLEGRO_EVENT_TIMER) menu_timer_wait = 0;
261
262 if (al_get_next_event(event_queue, &ev))
263 {
264 if (ev.type == ALLEGRO_EVENT_DISPLAY_RESIZE)
265 {
266 // check to see if we have more resize events piling up
267 ALLEGRO_EVENT ev2;
268
269 while (al_get_next_event(event_queue, &ev2))
270 {
271 if (ev2.type == ALLEGRO_EVENT_DISPLAY_RESIZE) ev = ev2;
272 else ret = proc_events(ev2, ret);
273 }
274 proc_screen_change(ev.display.width, ev.display.height, disp_x_curr, disp_y_curr, fullscreen);
275 }
276 else ret = proc_events(ev, ret);
277 }
278 }
279
280 if (game_exit) // if called from menu only do key check for active local player
281 {
282 clear_keys(active_local_player);
283 player_key_check(active_local_player);
284 function_key_check();
285 if (menu_timer_wait) done = 0;
286 }
287 else // this is run if a game is in progress
288 {
289 function_key_check();
290 extern int level_done;
291
292 for (int p=0; p<NUM_PLAYERS; p++)
293 if (players[p].active) // cycle all active players
294 {
295 if (players[p].control_method == 0) // local single player control
296 {
297 if (level_done) add_game_move(passcount, 6, 0, 0); // insert level done into game move
298 clear_keys(p);
299 player_key_check(p);
300 set_comp_move_from_controls(p);
301 if (players1[p].comp_move != players1[p].old_comp_move)
302 {
303 players1[p].old_comp_move = players1[p].comp_move;
304 add_game_move(passcount, 5, p, players1[p].comp_move);
305 }
306 }
307 if (players[p].control_method == 1) rungame_key_check(p, ret); // run game from file
308 #ifdef NETPLAY
309 if (players[p].control_method == 3) server_local_control(p);
310 if (players[p].control_method == 4) client_local_control(p);
311 #endif
312 set_controls_from_game_move(p); // common for all players
313 } // end of active player iterate
314 proc_game_move(); // run once per frame to process system messages from game_move
315 } // end of if (!game_exit)
316 }
317 //printf("ret:%d\n", ret);
318 return ret;
319}
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Mark Oates
Member #1,146
March 2001
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Doctor Cop said: I am using C so I can't use C++ strings! Ah, okie dokie. 👍 |
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Michael Weiss
Member #223
April 2000
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You said: I can't convert str[256] to a char* and that's the real problem. Why can't you convert str[256] to a char* ? Are you trying to get a string to pass to 'al_draw_text()' ? Can you post some code that shows what you are trying to convert to what? Are you trying to build a string from char's returned from events? 1
2// setup
3char str[256];
4str[0] = NULL;
5pos = 0;
6
7// get a char from events and add it to the string
8str[pos] = event.keyboard.unichar;
9pos++;
10str[pos] = NULL; // make sure to terminate the string with NULL
11
12// display the string
13al_draw_text(font, color, x, y, 0, str);
this will work, I've done it many times. char str[256] is an array of char Maybe I'm missing something and you're trying to do something else, let us know.
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Edgar Reynaldo
Major Reynaldo
May 2007
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Doctor Cop said:
I want to create a function which accepts's key presses and displays them in a rectangular box (field). here's the logic. Here's my updated version but still not working. showing signs of memory leak, Please Help! ... char* str1;
You're missing some fundamentals of C programming. First of all, 'str1' in your code there is just a pointer. It is NOT a string. It's a pointer of type char. That means it points to a char value. You have to allocate memory for the string somewhere. Second of all you didn't initialize the value of 'str1'. Which means it could hold ANY value. Doctor Cop said: I can't convert str[256] to a char* and that's the real problem. Uh, why not? Did your compiler output an error? It shouldn't. 1const int BUFSIZE = 1024;
2char buf[BUFSIZE] = {0};
3
4/// Option one, direct memory access
5buf[0] = 'a';
6
7/// Option two, string concatenation
8strcat(buf , "a");
9
10/// Option three, format string
11sprintf(buf , "%c" , 'a');
12
13char* alias = &buf[0];/// Take the address of the first element of the char array
14char* alias2 = buf;/// direct assignment works
Quote: If there's a way to create an input field like some library for allegro5 or code for that, please share. Here's an example of how to use an ALLEGRO_EVENT_KEY_CHAR event to create an input field : https://github.com/EdgarReynaldo/EagleGUI/blob/master/TINS2017/src/Game.cpp#L380-L443 My Website! | EAGLE GUI Library Demos | My Deviant Art Gallery | Spiraloid Preview | A4 FontMaker | Skyline! (Missile Defense) Eagle and Allegro 5 binaries | Older Allegro 4 and 5 binaries | Allegro 5 compile guide |
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Doctor Cop
Member #16,833
April 2018
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Edgar Reynaldo:- You said and I quote "Uh, why not? Did your compiler output an error? It shouldn't.", Thanx for your link:- https://github.com/EdgarReynaldo/EagleGUI/blob/master/TINS2017/src/Game.cpp#L380-L443, I will make utilization of your code in future but for now, I want to know what I am doing wrong. Michael Weiss:- For now, I replaced my code with your code.
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Edgar Reynaldo
Major Reynaldo
May 2007
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Doctor Cop said: Thank you for your advice and I was told that char* is a new way to initialize a string so that's why it happened. You have to understand what is happening when you declare a char* like that. This code : char* str = "some_text_goes_here"; actually translates to : static char str_array[20] = {'s','o','m','e','_','t','e','x','t','_', 'g','o','e','s','_','h','e','r','e','\0'}; char* str = &str_array[0]; The compiler declares a static string and gives you a pointer to it. Quote: Yes my compiler throws an error:- C++11 doesn't support conversion from char to a string. You said you're using C, not C++11. Make up your mind. It makes a difference. Quote:
Thank you for your suggestion but I already tried it and it successfully compiled but it produces a runtime error. You're not using events properly at all. You HAVE to check the event type before you access the event union or else you will get complete garbage. Try reading the manual. http://liballeg.org/a5docs/trunk/events.html My Website! | EAGLE GUI Library Demos | My Deviant Art Gallery | Spiraloid Preview | A4 FontMaker | Skyline! (Missile Defense) Eagle and Allegro 5 binaries | Older Allegro 4 and 5 binaries | Allegro 5 compile guide |
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Doctor Cop
Member #16,833
April 2018
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I want to make a GUI input field function which I can use for c and c++ both. If I use any GUI API for my game instead of trying to create my own, will it be the optimal solution, I mean will my game become large by adding additional library just for GUI purpose.
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Edgar Reynaldo
Major Reynaldo
May 2007
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In C++, you can't assign the value of a const char* (a string in C++) to a char*. It's illegal because the memory isn't yours. You have to declare your own buffer. char* str = "abc";/// Illegal in C++, deprecated in C /// "abc" is a static const char array /// and it is illegal to remove the const without a cast You don't need a GUI library for a single widget. Check the event type first, and then access the union. 1if (ev.type == EAGLE_EVENT_KEY_CHAR) {
2 int kc = ev.keyboard.keycode;
3 int ascii = ev.keyboard.unichar;
4 if (isalpha(ascii) || isnum(ascii) || isspace(ascii)) {
5 buf[index++] = (char)ascii;
6 }
7 else {
8
9 switch (kc) {
10 case ALLEGRO_KEY_LEFT :
11 --index;
12 if (index < 0) {index = 0;}
13 break;
14 case ALLEGRO_KEY_RIGHT :
15 ++index;
16 if (index >= BUFSIZE) {index = BUFSIZE - 1;}
17 case ALLEGRO_KEY_ENTER : finish(); break;
18 case ALLEGRO_KEY_BACKSPACE : erase_current(); break;
19 case ETC : break;
20 default : break;
21 };
22}
This should give you an idea of how to monitor keyboard events. My Website! | EAGLE GUI Library Demos | My Deviant Art Gallery | Spiraloid Preview | A4 FontMaker | Skyline! (Missile Defense) Eagle and Allegro 5 binaries | Older Allegro 4 and 5 binaries | Allegro 5 compile guide |
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Doctor Cop
Member #16,833
April 2018
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Thanks for your help and now I am going to use your library for GUI - (EAGLE5). What is SantaHack2016? again thanks and especially because of EAGLE5.cbp. I love code blocks builds.
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Edgar Reynaldo
Major Reynaldo
May 2007
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Eagle5 doesn't have an input widget yet. Eagle4 has integer, floating, and string entry widgets. But you can write one very easily. I can help you write an input widget if you want. My Website! | EAGLE GUI Library Demos | My Deviant Art Gallery | Spiraloid Preview | A4 FontMaker | Skyline! (Missile Defense) Eagle and Allegro 5 binaries | Older Allegro 4 and 5 binaries | Allegro 5 compile guide |
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bamccaig
Member #7,536
July 2006
 |
Something that was hinted at, but not fully explained, is the difference between `char []` and `char *` and what they're used for. An array, which is indicated by the square brackets `[]` allocates a sequence of bytes on the program's call stack. This is just like other local variables that you define, like int and char. It exists until the function returns, and is automatically released. A char pointer can either point to a single character, or to an array of characters, or NULL which signifies that memory has not been allocated yet, or garbage if you forget to initialize it (never do this because it's an obscure crash waiting to happen). The character or characters that you point to can either be on the stack or on the heap. The heap is like a pool of memory that you can allocate that survives even when a function returns. It is accessible from anywhere in the program as long as you know its address in memory. In C, you use the malloc family of functions to allocate memory on the heap, and in C++ you use the new and new[] operators. Anything that you allocate in this way must be cleaned up after using free() for malloc() style allocations and the delete or delete[] operators for new allocations. A memory leak is said to have occurred when you forget to do this. 1#include <assert.h>
2#include <stdio.h>
3#include <stdlib.h>
4#include <string.h>
5
6int main(int argc, char * argv[])
7{
8 char c = 'A';
9 const char * const cs = "static string of characters";
10 char s[255] = "string of characters";
11
12 char * pc = &c; // pc points to c, which contains 'A'.
13 char * ps = s; // ps points to s, which contains "string of characters" (which is nul-byte terminated).
14
15 // dc is a single character (not a string!) allocated on the heap.
16 // It is initially pointing to garbage, but then I assign 'B' to its memory slot.
17 char * dc = malloc(sizeof(char) * 1);
18 assert(dc);
19 *dc = 'B';
20
21 // ds is a character array allocated on the heap with a maximum length of 512
22 // characters. If this is used as a C string then it can only store 511 characters
23 // plus the nul-terminating character. The actual string is garbage right now.
24 // We have allocated the memory, but not initialized it yet.
25 char * ds = malloc(sizeof(char) * 512);
26 assert(ds);
27
28 // This is one way to initialize it. You can also use `calloc` instead which does
29 // this for you. This makes it an empty string "" (in a 512 character array).
30 memset(ds, 0, 512);
31
32 snprintf(ds, 512,
33 "c='%c' cs='%c' s=\"%s\", pc='%c', ps=\"%s\", dc='%c', ds=\"%s\"",
34 c, *cs, s, *pc, ps, *dc, ds);
35
36 puts(ds);
37
38 // Must release the memory when we're done with it.
39 free(dc);
40 free(ds);
41
42 return 0;
43}
In the snippet above I've tried to demonstrate the basic ways that character arrays and pointers are used. The thing that you were forgetting to do was allocate memory for the string. Whether you should do this on the stack or heap depends on how big it will be and whether you need it only temporarily or you need to be able to return it from a function. This is all about memory management. C and to an extent C++ put this burden on you do manage it. It's fun to do, but it's also hard to do perfectly. You definitely should try to understand these concepts now because it'll take a while to really get full control of this. -- acc.js | al4anim - Allegro 4 Animation library | Allegro 5 VS/NuGet Guide | Allegro.cc Mockup | Allegro.cc <code> Tag | Allegro 4 Timer Example (w/ Semaphores) | Allegro 5 "Winpkg" (MSVC readme) | Bambot | Blog | C++ STL Container Flowchart | Castopulence Software | Check Return Values | Derail? | Is This A Discussion? Flow Chart | Filesystem Hierarchy Standard | Clean Code Talks - Global State and Singletons | How To Use Header Files | GNU/Linux (Debian, Fedora, Gentoo) | rot (rot13, rot47, rotN) | Streaming |
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Doctor Cop
Member #16,833
April 2018
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bamccaig: Thanks for this information, I can't express how glad I am! Edgar Reynaldo: Thanks man, I really appreciate that but I already ripped off the logic from SDL's "TextInput" function.
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