anononamemo/42_Piscine_Reloaded

42_Piscine_Reloaded

42_Piscine_Reloaded

The Piscine was good but the time has past. This serie of exercises will help you to remind all the basics you’ve learned during the piscine. Functions, loops, pointers, structures, let’s remind together the syntactic and semantic bases of the C

Contents

IV Exercise 00 : Oh yeah, mooore...

1. Task:

$> ls -l
total 42
drwx--xr-x  2 login  wheel  XX Jun  1 20:47 test0
-rwx--xr--  1 login  wheel   4 Jun  1 21:46 test1
dr-x---r--  2 login  wheel  XX Jun  1 22:45 test2
-r-----r--  2 login  wheel   1 Jun  1 23:44 test3
-rw-r----x  1 login  wheel   2 Jun  1 23:43 test4
-r-----r--  2 login  wheel   1 Jun  1 23:44 test5
lrwxr-xr-x  1 login  wheel   5 Jun  1 22:20 test6 -> test0
$>

Remember about -h

2. man touch is reads

-t      Change the access and modification times to the specified time instead of the current time of day.  The argument is of the form
             ``[[CC]YY]MMDDhhmm[.SS]'' where each pair of letters represents the following:
                   CC      The first two digits of the year (the century).
                   YY      The second two digits of the year.  If ``YY'' is specified, but ``CC'' is not, a value for ``YY'' between 69 and 99 results in a ``CC''
                           value of 19.  Otherwise, a ``CC'' value of 20 is used.
                   MM      The month of the year, from 01 to 12.
                   DD      the day of the month, from 01 to 31.
                   hh      The hour of the day, from 00 to 23.
                   mm      The minute of the hour, from 00 to 59.
                   SS      The second of the minute, from 00 to 61.

             If the ``CC'' and ``YY'' letter pairs are not specified, the values default to the current year.  If the ``SS'' letter pair is not specified, the
             value defaults to 0.

---

3. Result:

touch -h -t "06012220" test6

V Exercise 01 : Z

---

1. Result:

z[enter]

VI Exercise 02 : clean

In a file called clean place the command line that will search for all files - in the current directory as well as in its sub-directories - with a name ending by ~, or with a name that start and end by #

• The command line will show and erase all files found.
• Only one command is allowed: no ’;’ or ’&&’ or other shenanigans.

1. You remember about - touch none{0..10}~ for create 10 file's
2. -name

-name pattern True if the last component of the pathname being examined matches pattern. Special shell pattern matching characters (['', ]'', *'', and ?'') may be used as part of pattern. These characters may be matched explicitly by escaping them with a backslash (``'').

3. We will use next flags:

-print - verbose output -delete - all know about this, read this, for all information https://rtfm.co.ua/komanda-find-i-eyo-opcii-v-primerax/ -name - input your find's name -exec ls -l {} \; - more -o - connection

---

4. Result:

find . -name "#*" -print -delete -o -name "*#" -delete -print -o -name "*~" -delete -print

VII Exercise 03 : find_sh

---

1. Result:

find . "*.sh" -print | awk -F "." '/.sh/{ print $2 }' | awk -F "/" '{ print $2 }'

man awk

VIII Exercise 04 : MAC

1. I will use grep
2. man ifconfig
3. man awk

---

4. Result:

ifconfig en0 | grep ether -w | awk -F " " '{ print $2 }'

IX Exercise 05 : Can you create it ?

---

1. Result:

touch '"\?$*’KwaMe’*$?\"'

p.s. Simple - '' or echo 42 > '"\?$*’KwaMe’*$?\"'

X Exercise 06 : ft_print_alphabet

1. Task:

Create a function that displays the alphabet in lowercase, on a single line, by ascending order, starting from the letter ’a’.

2. Classic

This function is easier to enter, that would constantly use. void - is NONE type, func - return NONE, but put char character

void ft_putchar(char c)
{
  write(1, &c, 1);
}

2.1 man ASCII

      97  a    98  b    99  c   100  d   101  e   102  f   103  g
     104  h   105  i   106  j   107  k   108  l   109  m   110  n   111  o
     112  p   113  q   114  r   115  s   116  t   117  u   118  v   119  w
     120  x   121  y   122  z

(i >= 97 && i <= 122) while i fits the condition

---

3. Result:

void ft_print_alphabet(void)
{
  int i = 97;
  while (i >= 97 && i <= 122)
    ft_putchar(i++);
  ft_putchar('\n');
}

XI Exercise 07 : ft_print_numbers

1. Task:

Create a function that displays all digits, on a single line, by ascending order.

2. man ascii:

      48  0    49  1    50  2    51  3    52  4    53  5    54  6    55  7
      56  8    57  9

---

3. Result:

void ft_print_numbers(void)
{
  int i = 48;
  while (i >=47 && i <= 57)
    ft_putchar(i++);
  ft_putchar('\n');
}

XII Exercise 08: ft_is_negative

1. Task:

Create a function that displays ’N’ or ’P’ depending on the integer’s sign entered as a parameter. If n is negative, display ’N’. If n is positive or null, display ’P’.

---

2. Result:

void ft_is_negative(int n)
{
  if (n < 0)
    ft_putchar('N');
  else if (n > 0)
    ft_putchar('P');
  else
    ft_putchar('P');
}

XIII Exercise 09 : ft_ft

1. Task:

Create a function that takes a pointer to int as a parameter, and sets the value "42" to that int.

2. About pointers:

For check pointer, write program:

int main()
{
  int i	= 42;

  ft_ft(&i);
  return(0);
}

Attention in terminal was:

ft_ft.c:14:9: warning: incompatible integer to pointer conversion passing 'int' to
      parameter of type 'int *'; take the address with & [-Wint-conversion]
  ft_ft(i);
        ^
        &

This message was displayed, because we did not insert a pointer to the link

---

3. Result

void ft_ft(int *nbr)
{
  int c;
  c = *nbr;
}

XIV Exercise 10 : ft_swap

1. Task:

Create a function that swaps the value of two integers whose addresses are entered as parameters.

Here’s how it should be prototyped: void ft_swap(int *a, int *b);

2. About pointer's:

Watch video - it's help you. Then, need understand, why I use pointers? Don't remember - Allowed functions : None

For check result, I was used:

int main()
{
  int a	= 1;
  int b	= 2;

  ft_swap(&a, &b);
  return(0);
}

---

3. Result:

void ft_swap(int *a, int *b)
{
  char c;
  c = *a;
  *a = *b;
  *b = c;
}

XV Exercise 11 : ft_div_mod

1. Task:

Create a function ft_div_mod prototyped like this : void ft_div_mod(int a, int b, int *div, int *mod);

This function divides parameters a by b and stores the result in the int pointed by div. It also stores the remainder of the division of a by b in the int pointed by mod.

2. About div & standart operation in C

Operator name	Syntax	C++ prototype examples
Multiplication	a * b	K::operator *(S b);
Division	a / b	K::operator /(S b);
Modulo	a % b	R K::operator %(S b);

2.1 For check this exercise:

int main()
{
  int a = 41;
  int b = 11;
  int *div;
  int *mod;

  ft_div_mod(a, b, div, mod);

  printf("%d\n", *div);
  printf("%d\n", *mod);

  return(0);
}

don't remember about #include <stdio.h>

---

3. Result

void ft_div_mod(int a, int b, int *div, int *mod)
{
  *div = a / b;
  *mod = a % b;
}

XVI Exercise 12 : ft_iterative_factorial

1. Task:

Create an iterated function that returns a number. This number is the result of a factorial operation based on the number given as a parameter.

If there’s an error, the function should return 0.

Here’s how it should be prototyped : c int ft_iterative_factorial(int nb);

Your function must return its result in less than two seconds.

2. About factorial:

$$7! = 1 * 2 * 3 * 4 * 5 * 6 * 7 0! = 1$$

---

3. Result:

int ft_iterative_factorial(int nb)
{
  int res;
  int i;

  res =	1;
  i = 1;

  if (nb >= 0 && nb <= 12)
    {
      while (i <= nb)
        res *= i++;
      return(res);
    }
  else
    return(0);
}

XVII Exercise 13 : ft_recursive_factorial

1. Task:

Reproduce the behavior of the function strlen (man strlen). Here’s how it should be prototyped:

 int ft_strlen(char *str);

2. Me help's watch this video:Рекурсия. Репка и матрёшка

---

3. Result:

int ft_recursive_factorial(int nb)
{
  if (nb == 0)
    return(1);
  else if (nb < 0 || nb > 12)
    return(0);
  else
    {
      c = c * nb;
      ft_recursive_factorial(nb -1);
    }
  return (c);
}

p.s. Check this: else if (nb < 0 || nb > 12), maybe is LYING? p.s.s. use global value.

XVIII Exercise 14 : ft_sqrt

1. Task:

Create a function that returns the square root of a number (if it exists), or 0 if the square root is an irrational number. Here’s how it should be prototyped :

int ft_sqrt(int nb);

Your function must return its result in less than two seconds.

2. About square, watch video Быстрое вычисление квадратных корней

---

3. Result:

int ft_sqrt(int nb)
{
  int i = 1;

  if (nb < 0 || nb >= 32767)
    return(0);
  else
    {
      while (i < nb && (i * i) < nb)
      	    i++;
    }
  return (i);
}

p.s. Rememder about int - if (nb < 0 || nb >= 32767)

XIX Exercise 15 : ft_putstr

Classic:

#include <unistd.h>

void ft_putstr(char *str)
{
  while (*str)
    write(1, str++, 1);
}

XX Exercise 16 : ft_strlen

Classic:

int ft_strlen(char *str)
{
  int len = 0;

  while (*str)
    {
      len++;
      str++;
    }
  return(len);
}

Check this:

int main()
{
  char str[] = "Hello world";
  printf("Len of %s = %d\n", str, ft_strlen(str));
  return(0);
}

p.s., don't remember about: #include <stdio.h>, if you want check this exercize

XXI Exercise 17 : ft_strcmp

1. About strcmp:

DESCRIPTION
     The strcmp() and strncmp() functions lexicographically compare the null-
     terminated strings s1 and s2.

     The strncmp() function compares not more than n characters.  Because
     strncmp() is designed for comparing strings rather than binary data,
     characters that appear after a `\0' character are not compared.

RETURN VALUES
     The strcmp() and strncmp() functions return an integer greater than,
     equal to, or less than 0, according as the string s1 is greater than,
     equal to, or less than the string s2.  The comparison is done using
     unsigned characters, so that `\200' is greater than `\0'.

2. Source of strcmp:

/* Compare S1 and S2, returning less than, equal to or
   greater than zero if S1 is lexicographically less than,
   equal to or greater than S2.  */
int
STRCMP (const char *p1, const char *p2)
{
  const unsigned char *s1 = (const unsigned char *) p1;
  const unsigned char *s2 = (const unsigned char *) p2;
  unsigned char c1, c2;
  do
    {
      c1 = (unsigned char) *s1++;
      c2 = (unsigned char) *s2++;
      if (c1 == '\0')
        return c1 - c2;
    }
  while (c1 == c2);
  return c1 - c2;
}

Note this: return only value c1 - c2;

3. Result:

int ft_strcmp(char *s1, char *s2)
{
  int lenS1 = 0;
  int lenS2 = 0;
  while (*s1)
    {
      lenS1++;
      s1++;
    }
  while	(*s2)
    {
      lenS2++;
      s2++;
    }

  return (lenS2 - lenS1);
}

How to check this?

int main()
{
  char str1[] = "Hello world";
  char str2[] = "World Hello1";
  printf("%d\n", ft_strcmp(str1, str2));
  return(0);
}

p.s., don't remember about: #include <stdio.h>, if you want check this exercize

XXII Exercise 18 : ft_print_params

1. Task:

$>./a.out test1 test2 test3
test1 test2
test3 $>

DO IT!

2. Result:

#include <unistd.h>

void ft_putchar(char c)
{
  write(1, &c, 1);
}

void ft_putstr(char *str)
{
  while	(*str)
    ft_putchar(*str++);
  ft_putchar('\n');
}

int main(int argc, char **argv)
{
  int i = 1;

  if (argc > 1)
      while(argv[i])
          ft_putstr(argv[i++]);
  return(0);
}

p.s. - use (argc > 1), remember about this!

XXIII Exercise 19 : ft_sort_params

1. Task:

> • We’re dealing with a program here, you should therefore have a function main in your .c file.
> • Create a program that displays its given arguments sorted by ascii order.
> • It should display all arguments, except for argv[0].
> • All arguments have to have their own line.



## CXXIV Exercise 20 : ft_strdup
## XXV Exercise 21 : ft_range
## XXVI Exercise 22 : ft_abs.h
## XXVIIExercise 23 : ft_point.h
## XXVIIIExercise 24 : Makefile
## XXIX Exercise 25 : ft_foreach
## XXX Exercise 26 : ft_count_if
## XXXI Exercise 27 : display_file
## XXXIIRendu et peer-évaluation
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https://github.com/adam-p/markdown-here/wiki/Markdown-Cheatsheet
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