/alx-low_level_programming

Alx SE programming in C

Primary LanguageC

ALX LOW LEVEL PROGRAMMING IN C

Low Level Programming :octocat:

Each folder in this repository illustrates an essential concept of programming, specific to the C programming language. The file names reference the concepts (i.e. pointers, recursion, malloc, free, structures, function pointers, variadic functions, linked lists, etc) Inside these folders are files containing bash scripts and functions around that particular concept. Some functions are re-creations of functions found in the C standard libraries (i.e. _strcpy, _strlen, etc).

Execution

To compile and run the C files, the following command is used

gcc -Wall -pedantic -Werror -Wextra -std=gnu89 main_file.c other_files.c -o a

This command is used to compile the C files main_file.c and other_files.c into an executable file called a.
Once the above command has executed successfully, an executable file appear on your folder. Now use the following command to execute

./a

The flags -Wall, -pedantic, -Werror, and -Wextra are used to enable warning messages in the compiler. The flag -std=gnu89 specifies that the C standard to use is C89.
The files {main_file.c} and {other_file.c} are C source code files that contain the code for the program.

Here is a breakdown of the meaning of each flag:

  • -Wall enables all warning messages.
  • -pedantic enables all warnings that are not strictly required by the C standard, but are considered to be good coding practice. E.g. if you use a variable that is not initialized, or a type cast that is not necessary.
  • -Werror turns all warnings into errors.
  • -Wextra enables additional warnings that are not enabled by default.
  • -std=gnu89 specifies that the C standard to use is C89.

Memory Leaks

A memory leak is a type of resource leak that occurs when a program fails to release memory that it no longer needs. This can happen when a program allocates memory for an object, but then fails to deallocate the memory when the object is no longer needed.

The command used with GCC to check for memory leaks is -fsanitize=leak. This flag enables the AddressSanitizer tool, which can detect memory leaks and other memory errors.

To use the -fsanitize=leak flag, you need to compile your code with the gcc compiler. For example, to compile a C file called my_program.c with the -fsanitize=leak flag, you would use the following command:

gcc -fsanitize=leak my_program.c -o my_program

Once you have compiled your code, you can run it with the valgrind tool to check for memory leaks. For example, to run the my_program executable with valgrind, you would use the following command:

valgrind --tool=memcheck --leak-check=yes ./my_program

If there are any memory leaks in your code, valgrind will report them.

Here are some other flags that can be used with -fsanitize=leak:

  • -fsanitize-address enables AddressSanitizer to detect other memory errors, such as use-after-free and double-free errors.
  • -fsanitize-leak-check-heuristic enables AddressSanitizer to use heuristics to detect memory leaks that are not otherwise detected.
  • -fsanitize-leak-check-after=N specifies the number of blocks that AddressSanitizer should check for leaks after the program terminates.

Environment

  • Language: C
  • OS: Ubuntu 14.04 LTS
  • Compiler: gcc 4.8.4
  • Style guidelines: Betty style