TryCatchC is a C module implementing the try/catch mechanism available in other programming languages but missing in C. It is based on the setjmp/longjmp functions. It supports recursive incursion of try/catch blocks, forward of uncaught exception to the upper level try/catch block if any, exception raised by signals like SIGSEV (non ANSI C feature), shared handling of several exceptions, user-defined default handler for uncaught exception, trace of raised exceptions toward a stream, and user-defined exceptions. It is multithread safe.
- Copy this repository
wget https://github.com/BayashiPascal/TryCatchC/archive/main.zip
unzip main.zip
mv TryCatchC-main TryCatchC
rm main.zip
- Compile and install
cd TryCatchC
make
sudo make install
cd -
- Optionnally you can delete the repository
rm -rf TryCatchC
- Then use it in your project, for example as follows:
#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include <TryCatchC/trycatchc.h>
int main() {
Try {
if (isnan(0./0.)) Raise(TryCatchException_NaN);
} Catch (TryCatchException_NaN) {
printf("Caught exception NaN\n");
} EndCatch;
return 0;
}
- Compile as follows:
gcc -c main.c
gcc main.o -ltrycatchc -lm -o main
- Run with
./main. Output:
Caught exception NaN
More examples can be found in main.c of this repository.
The dummy example below:
Try {
int e = 0;
Try {
/* something which doesn't use e */
} CatchDefault {
/* something which uses e */
} EndCatch;
/* something which uses e */
} EndCatch;
raises warning: variable ‘e’ might be clobbered by ‘longjmp’ or ‘vfork’ [-Wclobbered] when compiled with gcc -Wextra -On -c main.c where n>0 (gcc --version is 10.1.0).
Searching on the web shows it's a known problem since forever (link). As far as I understand, the optimizer sees e unused in the Try block and delay its declaration into the CatchDefault block, after the setjmp occurs, hence the clobbering when it's used after the Try/Catch if the longjmp had occured.
The warning can be avoided by adding -Wno-clobbered to the compilation command and ignore this seemingly erroneous warning, or by declaring e as volatile to force the optimizer to leave the declaration where it is:
Try {
volatile int e = 0;
Try {
/* something which doesn't use e */
} CatchDefault {
/* something which uses e */
} EndCatch;
/* something which uses e */
} EndCatch;
If you want to return/goto from inside a Try block, you need to call TryCatchEnd() before returning, else the internal stack of frame of TryCatch gets inconsistent, leading to undefined behaviour. The example below shows the correct way to use return inside a Try block.
void fun(int a) {
Try {
...
if (...) {
TryCatchEnd();
return;
}
...
} EndCatch;
}
If you're returning from several levels of imbrication of Try blocks, you must call TryCatchEnd() as many time as you skip EndCatch by returning.
TryCatchC, a C implementation of the try/catch mechanism in C Copyright (C) 2021 Pascal Baillehache
This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with this program. If not, see http://www.gnu.org/licenses/.