Concepts

For this project, we expect you to look at these concepts:

Struggling with the sandbox? Try this: Using Docker & WSL on your local host
C programming

YouTube Video

Resources

Read or watch:

Everything you need to know to start with C.pdf (You do not have to learn everything in there yet, but make sure you read it entirely first)
Dennis Ritchie
“C” Programming Language: Brian Kernighan
Why C Programming Is Awesome
Learning to program in C part 1
Learning to program in C part 2
Understanding C program Compilation Process
Betty Coding Style
Hash-bang under the hood (Look at only after you finish consuming the other resources)
Linus Torvalds on C vs. C++ (Look at only after you finish consuming the other resources)

man or help:

gcc
printf (3)
puts
putchar

Learning Objectives

At the end of this project, you are expected to be able to explain to anyone, without the help of Google:

General

Why C programming is awesome
Who invented C
Who are Dennis Ritchie, Brian Kernighan and Linus Torvalds
What happens when you type gcc main.c
What is an entry point
What is main
How to print text using printf, puts and putchar
How to get the size of a specific type using the unary operator sizeof
How to compile using gcc
What is the default program name when compiling with gcc
What is the official C coding style and how to check your code with betty-style
How to find the right header to include in your source code when using a standard library function
How does the main function influence the return value of the program

Requirements

C

Allowed editors: vi, vim, emacs
All your files will be compiled on Ubuntu 20.04 LTS using gcc, using the options -Wall -Werror -Wextra -pedantic -std=gnu89
All your files should end with a new line
A README.md file at the root of the repo, containing a description of the repository
A README.md file, at the root of the folder of this project, containing a description of the project
There should be no errors and no warnings during compilation
You are not allowed to use system
Your code should use the Betty style. It will be checked using betty-style.pl and betty-doc.pl

Shell Scripts

Allowed editors: vi, vim, emacs
All your scripts will be tested on Ubuntu 20.04 LTS
All your scripts should be exactly two lines long ($ wc -l file should print 2)
All your files should end with a new line
The first line of all your files should be exactly #!/bin/bash

More Info

Betty linter

To run the Betty linter just with command betty <filename>:

Go to the Betty repository
Clone the repo to your local machine
cd into the Betty directory
Install the linter with sudo ./install.sh
emacs or vi a new file called betty, and copy the script below:

#!/bin/bash
# Simply a wrapper script to keep you from having to use betty-style
# and betty-doc separately on every item.
# Originally by Tim Britton (@wintermanc3r), multiargument added by
# Larry Madeo (@hillmonkey)

BIN_PATH="/usr/local/bin"
BETTY_STYLE="betty-style"
BETTY_DOC="betty-doc"

if [ "$#" = "0" ]; then
    echo "No arguments passed."
    exit 1
fi

for argument in "$@" ; do
    echo -e "\n========== $argument =========="
    ${BIN_PATH}/${BETTY_STYLE} "$argument"
    ${BIN_PATH}/${BETTY_DOC} "$argument"
done

Once saved, exit file and change permissions to apply to all users with chmod a+x betty
Move the betty file into /bin/ directory or somewhere else in your $PATH with sudo mv betty /bin/

You can now type betty <filename> to run the Betty linter!

Quiz questions

Question #0

In which category belongs the C programming language?

Compiled language
Interpreted language

Question #1

Which command can be used to compile a C source file?

c-compiler
gcc
bash

Question #2

What is the common extension for a C source file?

.py
.txt
.c
.cpp

Question #3

What is the common extension for a C header file?

.ch
.header
.hpp
.h

Question #4

Which of the following are both valid comment syntaxes in ANSI C, and Betty-compliant?

/* Comment /* nested */ */

# Comment

/* Comment */

// Comment

/*
 * Comment
 */

/*
Comment
*/

Question #5

What are the different steps to form an executable file from C source code

Preprocessing and compilation
Interpretation, compilation and assembly
Preprocessing, compilation, assembly, and linking
Compilation and linking
Interpretation, assembly and compilation

Tasks

0. Preprocessor

Write a script that runs a C file through the preprocessor and save the result into another file.

The C file name will be saved in the variable $CFILE
The output should be saved in the file c

julien@ubuntu:~/c/0x00$ cat main.c
#include <stdio.h>

/**
 * main - Entry point
 *
 * Return: Always 0 (Success)
 */
int main(void)
{
    return (0);
}
julien@ubuntu:~/c/0x00$ export CFILE=main.c
julien@ubuntu:~/c/0x00$ ./0-preprocessor
julien@ubuntu:~/c/0x00$ tail c
# 942 "/usr/include/stdio.h" 3 4

# 2 "main.c" 2


# 3 "main.c"
int main(void)
{
 return (0);
}
julien@ubuntu:~/c/0x00$

Repo:

GitHub repository: alx-low_level_programming
Directory: 0x00-hello_world
File: 0-preprocessor

1. Compiler

Write a script that compiles a C file but does not link.

The C file name will be saved in the variable $CFILE
The output file should be named the same as the C file, but with the extension .o instead of .c.
- Example: if the C file is main.c, the output file should be main.o

julien@ubuntu:~/c/0x00$ export CFILE=main.c
julien@ubuntu:~/c/0x00$ cat main.c
#include <stdio.h>

/**
 * main - Entry point
 *
 * Return: Always 0 (Success)
 */
int main(void)
{
    return (0);
}
julien@ubuntu:~/c/0x00$ ./1-compiler
julien@ubuntu:~/c/0x00$ ls
0-preprocessor  1-compiler   c            main.o
Makefile               100-intel      main.c  main.s
julien@ubuntu:~/c/0x00$ cat -v main.o | head
^?ELF^B^A^A^@^@^@^@^@^@^@^@^@^A^@>^@^A^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^P^B^@^@^@^@^@^@^@^@^@^@@^@^@^@^@^@@^@^K^@^H^@UHM-^IM-eM-8^@^@^@^@]M-C^@GCC: (Ubuntu 5.4.0-6ubuntu1~16.04.2) 5.4.0 20160609^@^T^@^@^@^@^@^@^@^AzR^@^Ax^P^A^[^L^G^HM-^P^A^@^@^\^@^@^@^\^@^@^@^@^@^@^@^K^@^@^@^@A^N^PM-^F^BC^M^FF^L^G^H^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^A^@^@^@^D^@M-qM-^?^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^C^@^A^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^C^@^B^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^C^@^C^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^C^@^E^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^C^@^F^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^C^@^D^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^H^@^@^@^R^@^A^@^@^@^@^@^@^@^@^@^K^@^@^@^@^@^@^@^@main.c^@main^@^@^@^@ ^@^@^@^@^@^@^@^B^@^@^@^B^@^@^@^@^@^@^@^@^@^@^@^@.symtab^@.strtab^@.shstrtab^@.text^@.data^@.bss^@.comment^@.note.GNU-stack^@.rela.eh_frame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
^@^@^@^H^@^@^@^H^@^@^@^@^@^@^@^X^@^@^@^@^@^@^@  ^@^@^@^C^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@M-^P^A^@^@^@^@^@^@^M^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^A^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@julien@ubuntu:~/c/0x00$

Repo:

GitHub repository: alx-low_level_programming
Directory: 0x00-hello_world
File: 1-compiler

2. Assembler

Write a script that generates the assembly code of a C code and save it in an output file.

The C file name will be saved in the variable $CFILE
The output file should be named the same as the C file, but with the extension .s instead of .c.
- Example: if the C file is main.c, the output file should be main.s

julien@ubuntu:~/c/0x00$ export CFILE=main.c
julien@ubuntu:~/c/0x00$ cat main.c
#include <stdio.h>

/**
 * main - Entry point
 *
 * Return: Always 0 (Success)
 */
int main(void)
{
    return (0);
}
julien@ubuntu:~/c/0x00$ ./2-assembler
julien@ubuntu:~/c/0x00$ ls
0-preprocessor  1-compiler  2-assembler c  main.c  main.s  Makefile
julien@ubuntu:~/c/0x00$ cat main.s
    .file   "main.c"
    .text
    .globl  main
    .type   main, @function
main:
.LFB0:
    .cfi_startproc
    pushq   %rbp
    .cfi_def_cfa_offset 16
    .cfi_offset 6, -16
    movq    %rsp, %rbp
    .cfi_def_cfa_register 6
    movl    $0, %eax
    popq    %rbp
    .cfi_def_cfa 7, 8
    ret
    .cfi_endproc
.LFE0:
    .size   main, .-main
    .ident  "GCC: (Ubuntu 5.4.0-6ubuntu1~16.04.2) 5.4.0 20160609"
    .section    .note.GNU-stack,"",@progbits
julien@ubuntu:~/c/0x00$

Repo:

GitHub repository: alx-low_level_programming
Directory: 0x00-hello_world
File: 2-assembler

3. Name

Write a script that compiles a C file and creates an executable named cisfun.

The C file name will be saved in the variable $CFILE

julien@ubuntu:~/c/0x00$ export CFILE=main.c
julien@ubuntu:~/c/0x00$ cat main.c
#include <stdio.h>

/**
 * main - Entry point
 *
 * Return: Always 0 (Success)
 */
int main(void)
{
    return (0);
}
julien@ubuntu:~/c/0x00$ ./3-name
julien@ubuntu:~/c/0x00$ ls
0-preprocessor  1-compiler   3-name  cisfun  main.o  Makefile
100-intel       2-assembler  c       main.c  main.s
julien@ubuntu:~/c/0x00$

Repo:

GitHub repository: alx-low_level_programming
Directory: 0x00-hello_world
File: 3-name

4. Hello, puts

Write a C program that prints exactly "Programming is like building a multilingual puzzle, followed by a new line.

Use the function puts
You are not allowed to use printf
Your program should end with the value 0

julien@ubuntu:~/c/0x00$ gcc -Wall -Werror -Wextra -pedantic -std=gnu89 4-puts.c && ./a.out
"Programming is like building a multilingual puzzle
julien@ubuntu:~/c/0x00$ echo $?
0
julien@ubuntu:~/c/0x00$

Repo:

GitHub repository: alx-low_level_programming
Directory: 0x00-hello_world
File: 4-puts.c

5. Hello, printf

Write a C program that prints exactly with proper grammar, but the outcome is a piece of art,, followed by a new line.

Use the function printf
You are not allowed to use the function puts
Your program should return 0
Your program should compile without warning when using the -Wall gcc option

julien@ubuntu:~/c/0x00$ gcc -Wall -Werror -Wextra -pedantic -std=gnu89 5-printf.c
julien@ubuntu:~/c/0x00$ ./a.out
with proper grammar, but the outcome is a piece of art,
julien@ubuntu:~/c/0x00$ echo $?
0
julien@ubuntu:~/c/0x00$

Repo:

GitHub repository: alx-low_level_programming
Directory: 0x00-hello_world
File: 5-printf.c

6. Size is not grandeur, and territory does not make a nation

Write a C program that prints the size of various types on the computer it is compiled and run on.

You should produce the exact same output as in the example Warnings are allowed
Your program should return 0
You might have to install the package libc6-dev-i386 on your Linux to test the -m32 gcc option

julien@ubuntu:~/c/0x00$ gcc 6-size.c -m32 -o size32 2> /tmp/32
julien@ubuntu:~/c/0x00$ gcc 6-size.c -m64 -o size64 2> /tmp/64
julien@ubuntu:~/c/0x00$ ./size32
Size of a char: 1 byte(s)
Size of an int: 4 byte(s)
Size of a long int: 4 byte(s)
Size of a long long int: 8 byte(s)
Size of a float: 4 byte(s)
julien@ubuntu:~/c/0x00$ ./size64
Size of a char: 1 byte(s)
Size of an int: 4 byte(s)
Size of a long int: 8 byte(s)
Size of a long long int: 8 byte(s)
Size of a float: 4 byte(s)
julien@ubuntu:~/c/0x00$ echo $?
0
julien@ubuntu:~/c/0x00$

Repo:

GitHub repository: alx-low_level_programming
Directory: 0x00-hello_world
File: 6-size.c

7. Intel

Write a script that generates the assembly code (Intel syntax) of a C code and save it in an output file.

The C file name will be saved in the variable $CFILE.
The output file should be named the same as the C file, but with the extension .s instead of .c.
- Example: if the C file is main.c, the output file should be main.s

julien@ubuntu:~/c/0x00$ export CFILE=main.c
julien@ubuntu:~/c/0x00$ cat main.c
#include <stdio.h>

/**
 * main - Entry point
 *
 * Return: Always 0 (Success)
 */
int main(void)
{
    return (0);
}
julien@ubuntu:~/c/0x00$ ./100-intel
julien@ubuntu:~/c/0x00$ cat main.s
    .file   "main.c"
    .intel_syntax noprefix
    .text
    .globl  main
    .type   main, @function
main:
.LFB0:
    .cfi_startproc
    push    rbp
    .cfi_def_cfa_offset 16
    .cfi_offset 6, -16
    mov rbp, rsp
    .cfi_def_cfa_register 6
    mov eax, 0
    pop rbp
    .cfi_def_cfa 7, 8
    ret
    .cfi_endproc
.LFE0:
    .size   main, .-main
    .ident  "GCC: (Ubuntu 5.4.0-6ubuntu1~16.04.2) 5.4.0 20160609"
    .section    .note.GNU-stack,"",@progbits
julien@ubuntu:~/c/0x00$

Repo:

GitHub repository: alx-low_level_programming
Directory: 0x00-hello_world
File: 100-intel

8. UNIX is basically a simple operating system, but you have to be a genius to understand the simplicity

Write a C program that prints exactly and that piece of art is useful" - Dora Korpar, 2015-10-19, followed by a new line, to the standard error.

You are not allowed to use any functions listed in the NAME section of the man (3) printf or man (3) puts
Your program should return 1
Your program should compile without any warnings when using the -Wall gcc option

julien@ubuntu:~/c/0x00$ gcc -Wall -Werror -Wextra -pedantic -std=gnu89 -o quote 101-quote.c
julien@ubuntu:~/c/0x00$ ./quote
and that piece of art is useful" - Dora Korpar, 2015-10-19
julien@ubuntu:~/c/0x00$ echo $?
1
julien@ubuntu:~/c/0x00$ ./quote 2> q
julien@ubuntu:~/c/0x00$ cat q
and that piece of art is useful" - Dora Korpar, 2015-10-19
julien@ubuntu:~/c/0x00$ grep printf < 101-quote.c
julien@ubuntu:~/c/0x00$ grep put < 101-quote.c
julien@ubuntu:~/c/0x00$

Repo:

GitHub repository: alx-low_level_programming
Directory: 0x00-hello_world
File: 101-quote.c

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README.md

README.md

Concepts

Resources

Learning Objectives

General

Requirements

C

Shell Scripts

More Info

Betty linter

Quiz questions

Question #0

Question #1

Question #2

Question #3

Question #4

Question #5

Tasks

0. Preprocessor

1. Compiler

2. Assembler

3. Name

4. Hello, puts

5. Hello, printf

6. Size is not grandeur, and territory does not make a nation

7. Intel

8. UNIX is basically a simple operating system, but you have to be a genius to understand the simplicity

Files

README.md

Latest commit

History

README.md

File metadata and controls

Concepts

Resources

Learning Objectives

General

Requirements

C

Shell Scripts

More Info

Betty linter

Quiz questions

Question #0

Question #1

Question #2

Question #3

Question #4

Question #5

Tasks

0. Preprocessor

1. Compiler

2. Assembler

3. Name

4. Hello, puts

5. Hello, printf

6. Size is not grandeur, and territory does not make a nation

7. Intel

8. UNIX is basically a simple operating system, but you have to be a genius to understand the simplicity