Segmentation fault while trying to draw triangles with C
Multi tool use
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Continuing on a previous question in a previous thread:
Hi guys! Part 2 of my bouncing ball questions. (previous question)
I'm still getting a segmentation fault in my code, but only while drawing the last element of an array. I have put in print-statements to see exactly where the code stops, and it is in the last iteration in the for loop below:
void draw_object(object_t *object)
{
for (int i = 0; i < object->numtriangles; i++) {
/* Translate triangle into middle of screen before drawing it */
object->model[i].tx = object->surface->w/2;
object->model[i].ty = object->surface->h/2;
/* Set new rotation and scale it down */
object->model[i].rotation = object->rotation;
object->model[i].scale = object->scale;
/* And draw it */
draw_triangle(object->surface, &object->model[i]);
printf("okn %d", i+1);
}
Now there are 478 elements in the group and it goes through 477 before the segmentation fault appears. If I change the second condition in the for loop to something like this:
for(int i=0, i<200, i++)
The segmentation fault appears after 199 iterations.
I have no idea why this is happening. I would think it is very unlikely that I run out of memory, especially when I can do 400 iterations without a problem until the last iteration.
All help is greatly appreciated! Thanks in advance.
c for-loop malloc
asked Nov 12 at 20:37
Peter
112
|
show 4 more comments
up vote
0
down vote
favorite
Continuing on a previous question in a previous thread:
Hi guys! Part 2 of my bouncing ball questions. (previous question)
I'm still getting a segmentation fault in my code, but only while drawing the last element of an array. I have put in print-statements to see exactly where the code stops, and it is in the last iteration in the for loop below:
void draw_object(object_t *object)
{
for (int i = 0; i < object->numtriangles; i++) {
/* Translate triangle into middle of screen before drawing it */
object->model[i].tx = object->surface->w/2;
object->model[i].ty = object->surface->h/2;
/* Set new rotation and scale it down */
object->model[i].rotation = object->rotation;
object->model[i].scale = object->scale;
/* And draw it */
draw_triangle(object->surface, &object->model[i]);
printf("okn %d", i+1);
}
Now there are 478 elements in the group and it goes through 477 before the segmentation fault appears. If I change the second condition in the for loop to something like this:
for(int i=0, i<200, i++)
The segmentation fault appears after 199 iterations.
I have no idea why this is happening. I would think it is very unlikely that I run out of memory, especially when I can do 400 iterations without a problem until the last iteration.
All help is greatly appreciated! Thanks in advance.
c for-loop malloc
asked Nov 12 at 20:37
Peter
112
3
Run your code through valgrind. If you're mismanaging memory, which it looks like you are, it will tell you where.
– dbush
Nov 12 at 20:39
2
I see no problems in the code presented, there's probably UB elsewhere.
– yano
Nov 12 at 20:41
2
Can't tell without a Minimal, Complete, and Verifiable example.
– Fred Larson
Nov 12 at 20:43
1
OK. Then notice that the output is line-buffered, so it would print198 okn- and then 199 would remain in the buffer. Addfflush(stdout);ornat the end of the printf, and you'd notice that it totally doesn't crash there. Also, now would be a good time to learn to use a proper debugger!
– Antti Haapala
Nov 12 at 20:56
1
Is there a good reason why you're printing the number after the newline? Why notok %dn?
– Barmar
Nov 12 at 21:20
|
show 4 more comments
up vote
0
down vote
favorite
up vote
0
down vote
favorite
Continuing on a previous question in a previous thread:
Hi guys! Part 2 of my bouncing ball questions. (previous question)
I'm still getting a segmentation fault in my code, but only while drawing the last element of an array. I have put in print-statements to see exactly where the code stops, and it is in the last iteration in the for loop below:
void draw_object(object_t *object)
{
for (int i = 0; i < object->numtriangles; i++) {
/* Translate triangle into middle of screen before drawing it */
object->model[i].tx = object->surface->w/2;
object->model[i].ty = object->surface->h/2;
/* Set new rotation and scale it down */
object->model[i].rotation = object->rotation;
object->model[i].scale = object->scale;
/* And draw it */
draw_triangle(object->surface, &object->model[i]);
printf("okn %d", i+1);
}
Now there are 478 elements in the group and it goes through 477 before the segmentation fault appears. If I change the second condition in the for loop to something like this:
for(int i=0, i<200, i++)
The segmentation fault appears after 199 iterations.
I have no idea why this is happening. I would think it is very unlikely that I run out of memory, especially when I can do 400 iterations without a problem until the last iteration.
All help is greatly appreciated! Thanks in advance.
c for-loop malloc
asked Nov 12 at 20:37
Peter
112
Continuing on a previous question in a previous thread:
Hi guys! Part 2 of my bouncing ball questions. (previous question)
I'm still getting a segmentation fault in my code, but only while drawing the last element of an array. I have put in print-statements to see exactly where the code stops, and it is in the last iteration in the for loop below:
void draw_object(object_t *object)
{
for (int i = 0; i < object->numtriangles; i++) {
/* Translate triangle into middle of screen before drawing it */
object->model[i].tx = object->surface->w/2;
object->model[i].ty = object->surface->h/2;
/* Set new rotation and scale it down */
object->model[i].rotation = object->rotation;
object->model[i].scale = object->scale;
/* And draw it */
draw_triangle(object->surface, &object->model[i]);
printf("okn %d", i+1);
}
Now there are 478 elements in the group and it goes through 477 before the segmentation fault appears. If I change the second condition in the for loop to something like this:
for(int i=0, i<200, i++)
The segmentation fault appears after 199 iterations.
I have no idea why this is happening. I would think it is very unlikely that I run out of memory, especially when I can do 400 iterations without a problem until the last iteration.
All help is greatly appreciated! Thanks in advance.
c for-loop malloc
c for-loop malloc
asked Nov 12 at 20:37
Peter
112
asked Nov 12 at 20:37
Peter
112
asked Nov 12 at 20:37
Peter
112
asked Nov 12 at 20:37
Peter
112
asked Nov 12 at 20:37
Peter
112
112
3
Run your code through valgrind. If you're mismanaging memory, which it looks like you are, it will tell you where.
– dbush
Nov 12 at 20:39
2
I see no problems in the code presented, there's probably UB elsewhere.
– yano
Nov 12 at 20:41
2
Can't tell without a Minimal, Complete, and Verifiable example.
– Fred Larson
Nov 12 at 20:43
1
OK. Then notice that the output is line-buffered, so it would print198 okn- and then 199 would remain in the buffer. Addfflush(stdout);ornat the end of the printf, and you'd notice that it totally doesn't crash there. Also, now would be a good time to learn to use a proper debugger!
– Antti Haapala
Nov 12 at 20:56
1
Is there a good reason why you're printing the number after the newline? Why notok %dn?
– Barmar
Nov 12 at 21:20
|
show 4 more comments
3
Run your code through valgrind. If you're mismanaging memory, which it looks like you are, it will tell you where.
– dbush
Nov 12 at 20:39
2
I see no problems in the code presented, there's probably UB elsewhere.
– yano
Nov 12 at 20:41
2
Can't tell without a Minimal, Complete, and Verifiable example.
– Fred Larson
Nov 12 at 20:43
1
OK. Then notice that the output is line-buffered, so it would print198 okn- and then 199 would remain in the buffer. Addfflush(stdout);ornat the end of the printf, and you'd notice that it totally doesn't crash there. Also, now would be a good time to learn to use a proper debugger!
– Antti Haapala
Nov 12 at 20:56
1
Is there a good reason why you're printing the number after the newline? Why notok %dn?
– Barmar
Nov 12 at 21:20
3
3
Run your code through valgrind. If you're mismanaging memory, which it looks like you are, it will tell you where.
– dbush
Nov 12 at 20:39
Run your code through valgrind. If you're mismanaging memory, which it looks like you are, it will tell you where.
– dbush
Nov 12 at 20:39
2
2
I see no problems in the code presented, there's probably UB elsewhere.
– yano
Nov 12 at 20:41
I see no problems in the code presented, there's probably UB elsewhere.
– yano
Nov 12 at 20:41
2
2
Can't tell without a Minimal, Complete, and Verifiable example.
– Fred Larson
Nov 12 at 20:43
Can't tell without a Minimal, Complete, and Verifiable example.
– Fred Larson
Nov 12 at 20:43
1
1
OK. Then notice that the output is line-buffered, so it would print
198 okn - and then 199 would remain in the buffer. Add fflush(stdout); or n at the end of the printf, and you'd notice that it totally doesn't crash there. Also, now would be a good time to learn to use a proper debugger!– Antti Haapala
Nov 12 at 20:56
OK. Then notice that the output is line-buffered, so it would print
198 okn - and then 199 would remain in the buffer. Add fflush(stdout); or n at the end of the printf, and you'd notice that it totally doesn't crash there. Also, now would be a good time to learn to use a proper debugger!– Antti Haapala
Nov 12 at 20:56
1
1
Is there a good reason why you're printing the number after the newline? Why not
ok %dn?– Barmar
Nov 12 at 21:20
Is there a good reason why you're printing the number after the newline? Why not
ok %dn?– Barmar
Nov 12 at 21:20
|
show 4 more comments
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oHAguq9cRWk9 XJ1Vnod8B
3
Run your code through valgrind. If you're mismanaging memory, which it looks like you are, it will tell you where.
– dbush
Nov 12 at 20:39
2
I see no problems in the code presented, there's probably UB elsewhere.
– yano
Nov 12 at 20:41
2
Can't tell without a Minimal, Complete, and Verifiable example.
– Fred Larson
Nov 12 at 20:43
1
OK. Then notice that the output is line-buffered, so it would print
198 okn- and then 199 would remain in the buffer. Addfflush(stdout);ornat the end of the printf, and you'd notice that it totally doesn't crash there. Also, now would be a good time to learn to use a proper debugger!– Antti Haapala
Nov 12 at 20:56
1
Is there a good reason why you're printing the number after the newline? Why not
ok %dn?– Barmar
Nov 12 at 21:20