C Labs

Experiments and short programs written in C.

Requirements

1. Docker or
2. Your preferred way of compiling C (e.g GCC).

Setup with Docker

The following command will build an image that can compile and run C programs, will bind this project folder to the container's /home/source/ and it will keep the container alive indefinetly so that the project can be worked on.

docker compose up --detach

Then access the container using the ID if known or the name which will always be clang:

docker exec -it clang /bin/bash

With access to the container switch the directory to find the project files e.g:

cd /home/source/hello

Compile programs and run binaries as needed:

# Compile the program:
gcc -o main ./main.c

# or with clang:
clang -g -Wall -std=c99 -o main ./main.c

# Run the program:
./main

The command can also be combined so that it tries to run after it is compiled:

clang -g -Wall -std=c99 -o main ./main.c && ./main

When done, exit the interactive terminal with Ctrl+C and remove the containers or type exit:

docker compose down

Programs can also be inspected for memory leaks using valgrind <file>:

root@567cbfe975b0:/home/project/source/malloc# valgrind ./main

==40== Memcheck, a memory error detector
==40== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
==40== Using Valgrind-3.13.0 and LibVEX; rerun with -h for copyright info
==40== Command: ./main
==40==
source: hello
target: Hello
==40==
==40== HEAP SUMMARY:
==40==     in use at exit: 0 bytes in 0 blocks
==40==   total heap usage: 2 allocs, 2 frees, 1,030 bytes allocated
==40==
==40== All heap blocks were freed -- no leaks are possible
==40==
==40== For counts of detected and suppressed errors, rerun with: -v
==40== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)

The clang static analyzer can also be used with scan-build:

scan-build clang main.c

The output should look similar to the following:

root@3fc228fa345f:/home/project/source/arrays# scan-build clang main.c
scan-build: Using '/usr/lib/llvm-16/bin/clang' for static analysis
scan-build: Analysis run complete.
scan-build: Removing directory '/tmp/scan-build-2024-01-14-233048-110-1' because it contains no reports.
scan-build: No bugs found.