I am trying to run the code
function [ outStruct ] = loadfile( filename )
fid = fopen(filename,'r');
vector=[];
i=1;
while ~feof(fid)
line=fget1(fid);
vector(i)=AnotherFunction(line);
i=i+1;
end
end
But I keep getting the error message 'Undefined function 'fget1' for input arguments of type 'double''.
This whole function is mostly a copy of something we did in class, where it seemed to run fine, so I don't know the problem here.
I think you mean fgetl, not fget1. Note that the last letter in the first one is an L, while in the second (your version) you've put a one.
Related
I am trying to print out the contents of a 2 dimensional array starting from a certain location in the array (since not all elements of the array are filled). The array contains pointers to a data structure I created called a node. Here is the print code:
void repository_print(int print_elements){
node *travTemp;
travTemp = main_list[highest_level][0];
while((travTemp->down)!=NULL){
while((travTemp->next)!=NULL){
printf(" {%d, %d}", travTemp->key, travTemp->d);
travTemp = travTemp->next;
}
travTemp = travTemp->down;
printf("\n");
}
}
Basically the array holds pointers to node elements in a sorted fashion. Each node contains a "key" attribute and a "d" attribute and I am just trying to go level by level and print out the {key, d} records cleanly. I keep getting a segfault when I call the print command in my main. I tried using gdb to debug it but it won't give me an actual line. It just says:
#0 0x0000000000400b2e in repository_print ()
#1 0x0000000000400722 in main ()
Does anyone how I can find the seg fault or why the seg fault is occurring? Thanks.
EDIT:
I did try compiling with -g and found that the error is occurring at the line "while((travTemp->next)!=NULL)". This is confusing to me because this attribute should not be NULL. I'll have to check the rest of my code. The main_list declaration is as follows in case anyone needs to know:
node *main_list[MAX_HEIGHT][MAX_LEVEL];
EDIT:
So following Felipe's advice I changed my print function to the following:
node *travTemp;
travTemp = main_list[highest_level][0];
while(travTemp!=NULL && (travTemp->down)!=NULL){
printf(" {%d, %d}", travTemp->next->key, travTemp->next->d);
travTemp = travTemp->next;
}
travTemp = main_list[highest_level+1][0];
printf("\n");
However, now, I'm getting a seg fault at the print statement line. If travTemp->next does not equal NULL what's the problem with travTemp->next->key? I have no idea why since these values should exist in the repository.
If main_list[highest_level][0] is NULL, then your initial attempt to test travTemp->next will fail. #Filipe has addressed getting more debugging info in the comments.
Update: if it isn't NULL but following travTemp seems to be the problem, perhaps it is some other illegal value. Not seeing how main_list was filled, can't say more than that.
I'm trying to read some data from Processing and write it to a file. The data is correct, since I can plot it without problem. However, when I attempt to write it to a file it throws me the following error:
Error, disabling serialEvent() for /dev/ttyACM0
null
Specifically, I've found out where the problem is. It's in this function:
void serialEvent(Serial myPort) {
int inByte = myPort.read();
if (inByte >= 0 && inByte <= 255)
{
// This is what makes the problem arise
output.println("test: " + inByte);
// ...
}
}
I've even changed the line output.println(); with this and then the same function works, printing it to the correct file (but it's obviously not what I want):
// This does work
point(mouseX, mouseY);
output.println(mouseX);
Any idea where the problem might be? I'm using arduino and it passes values from 0 to 255 from serial. The values seem correct, since I can plot them without problem. I've also tried changing println() for print() with no luck.
EDIT. After some testing, I find this really odd. This works:
point(mouseX, mouseY);
output.println(inByte);
While, without the point(), it doesn't work (same error). As a temporary solution, I can put the output.println at the end of the function, but this is obviously not a long-term solution.
I ended up doing a simple check in my code:
if (output != null) {
output.println(t + " " + inByte);
}
It just works. However, I think that polymorphism would be even better here. Having an object that absorbs the text if the output is not initialized, and that prints it to the file if it is.
I had the same problem but here is my solution and it works perfectly.
at the beginning of the code write sth like this:
boolean outputInitialized = false;
after output = createWriter(filename.txt); put following:
outputInitialized = true;
the output.print function has to be included in an if-function:
if (outputInitialized) {
output.println(filename);
}
i was practicing my C Prog Language
and i decided to create a salon with cashier features
it looks messy,
though i'm still learning
posted here: http://pastebin.com/B2XaaCYV
it say runtime error with variable "menu", but i tried to recheck it around 5x and i don't see any error with it.
the code is really simple
like xy[0][1] = default 0 = meaning not yet purchased. its value will be 0/1 only. it will be 1 when you actually purchase it after picking the hairstyle.
then of course
xy[1][i] means price of xy[0][i]
i tried using other techniques like removing of breaks and changing variable name, but still it says runtime error with variable menu
no idea what makes the error. so i wish someone can help me with this
scanf("%1s",&menu);
No! A char isn't a string at all. You want to get a single character, so use either getchar() or scanf("%c",&menu);.
A related error is in your core_return, where you try to read 3 characters into a single character. Also, don't call your main in a sub-routine. Instead return from the sub-routine and put a loop in your main. By the way, 'yes' and 'no' aren't valid. If you want to compare strings, you have to use strcmp:
// returns 1 if the user wants to go again
int another_menu(void)
{
char tmp[20];
printf("Do you want another service?");
for(;;){
scanf("%3s",tmp);
if(strcmp("y",tmp) || strcmp("yes",tmp))
return 0;
else if(strcmp("n",tmp) || strcmp("no",tmp))
return 1;
printf("Please specify either 'no' or 'yes': ");
}
}
Use compiler warnings in order to find your errors quicker (GCC: -Wall -Wextra).
Hello I am studying for a test for an intro to C programming class and yesterday I was trying to write this program to print out the even prime numbers between 2 and whatever number the user enters and I spent about 2 hours trying to write it properly and eventually I did it. I have 2 pictures I uploaded below. One of which displays the correct code and the correct output. The other shows one of my first attempts at the problem which didn't work correctly, I went back and made it as similar to the working code as I could without directly copying and pasting everything.
unfortunately new users aren't allowed to post pictures hopefully these links below will work.
This fails, it doesn't print all numbers in range with natural square root:
for (i = 2; i <= x; i++)
{
//non relevant line
a = sqrt(i);
aa = a * a;
if (aa == i);
printf("%d ",i);
}
source: http://i.imgur.com/WGG6n.jpg
While this succeeds, and prints even numbers with natural sqaure root
for (i = 2; i <= x; i++)
{
a = sqrt(i);
aa = a * a;
if (aa == i && ((i/2) *2) == i)
printf("%d ", i);
}
source: http://i.imgur.com/Kpvpq.jpg
Hopefully you can see and read the screen shots I have here. I know that the 'incorrect code' picture does not have the (i/2)*2 == i part but I figured that it would still print just the odd and even numbers, it also has the code to calculate "sqrd" but that shouldn't affect the output. Please correct me if I'm wrong on that last part though.
And Yes I am using Dev-C++ which I've read is kinda crappy of a program but I initally did this on code::blocks and it did the same thing...
Please I would very much appreciate any advice or suggestions as to what I did wrong 2 hours prior to actually getting the darn code to work for me.
Thank you,
Adam
your code in 'that' includes:
if (aa == i);
// ^
printf(...);
[note the ; at the end of the if condition]
Thus, if aa == i - an empty statement happens, and the print always occures, because it is out of the scope of the if statement.
To avoid this issue in the future, you might want to use explicit scoping1 [using {, } after control flow statements] - at least during your first steps of programming the language.
1: spartan programmers will probably hate this statement
Such errors are common. I use "step Over", "Step Into", "Break Points" and "watch window" to debug my program. Using these options, you can execute your program line by line and keep track of the variables used in each line. This way, u'll know which line is not getting executed in the desired way.
I have a function with an absurd number of return points, and I don't want to caveman each one, and I don't want to next through the function. Is there any way I can do something like finish, except have it stop on the return statement?
You can try reverse debugging to find out where function actually returns. Finish executing current frame, do reverse-step and then you should stop at just returned statement.
(gdb) fin
(gdb) reverse-step
There is already similar question
I think you're stuck setting breakpoints. I'd write a script to generate the list of breakpoint commands to run and paste them into gdb.
Sample script (in Python):
lines = open(filename, 'r').readlines()
break_lines = [line_num for line_num, line in enumerate(lines) if 'return' in line and
line_num > first and line_num <= last]
break_cmds = ['b %s:%d' % (filename, line_num) for line_num in break_lines]
print '\n'.join(break_cmds)
Set filename to the name of the file with the absurd function, first to the first line of the function (this is a quick script, not a C parser) and last to the number of the last line of the function. The output ought to be suitable for pasting into gdb.
Kind of a stretch, but the catch command can stop on many kinds of things (like forking, exiting, receiving a signal). You may be able to use catch catch (which breaks for exceptions) to do what you want in C++ if you wrap the function in try/finally. For that matter, if you break on a line inside the finally you can probably single-step through the return after that (although how much that will tell you about where it came from is highly dependent on optimization: common return cases are often folded by gcc).
How about taking this opportunity to break up what seems to be clearly a too-large function?
This question's come up before on SO. My answer from there:
Obviously you ought to refactor this function, but in C++ you can use this simple expedient to deal with this in five minutes:
class ReturnMarker
{
public:
ReturnMarker() {};
~ReturnMarker()
{
dummy += 1; //<-- put your breakpoint here
}
static int dummy;
}
int ReturnMarker::dummy = 0;
and then instance a single ReturnMarker at the top of your function. When it returns, that instance will go out of scope, and you'll hit the destructor.
void LongFunction()
{
ReturnMarker foo;
// ...
}