You get the correct results in grace, but not in the submit
server - This may happen because:
You have uninitialized variables. Grace seems to set
uninitialized variables to 0.
Your strings are missing a null character ('\0').
You are not declaring an array that is large enough.
When iterating over an array the code is going beyond
the array memory area (e.g., off by one).
You are passing to a function a pointer to a character
rather than a pointer to an array of characters.
Your code might be generating a segmentation fault (segfault) in the submit server
if, for a test, the submit server displays a message along the
lines:
"expected ... but output ended".
If you are missing a required function or has a typo in a
function (e.g., prontf instead of printf) you may get a message
similar to the following:
"collect2: error: ld returned 1 exit status"
ld represents the GNU linker (you can find additional information
by executing "man ld". Usually the last step in compiling a program
is to run ld (this is done on your behalf by GCC).
If your code is not compiling in the submit server it might be
due to a function that is not implemented. Provide an empty
body (with a dummy return value if needed) for functions you have not
implemented yet so your code compiles in the submit server.
You are returning a pointer to a local variable.
Check your pointer variables are initialized correctly.
You see the error
"ISO C90 forbids mixed declarations and code [-Wpedantic]".
The gcc alias for this class requires variables to be declared
at the top of a block. The following code will generate the
above error:
int main() {
printf("here\n");
int x;
return 0;
}
To correct the error, make int x; the first statement in the block.
If you get an error along the lines of "stack smashing" the problem
could be you are writing to an area you not supposed to access (e.g.,
array out of bounds access).
Using sizeof() incorrectly. For example, using sizeof() to determine
the size of an array parameter. In this case sizeof() will return
the number of bytes associated with a pointer type, not the number
of elements in the array.