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0x14-bit_manipulation

0-binary_to_uint.c

Write a function that converts a binary number to an unsigned int.

  • Prototype: unsigned int binary_to_uint(const char *b);
  • where b is pointing to a string of 0 and 1 chars
  • Return: the converted number, or 0 if
    • there is one or more chars in the string b that is not 0 or 1
    • b is NULL
julien@ubuntu:~/0x14. Binary$ cat 0-main.c
#include <stdio.h>
#include "main.h"

/**
 * main - check the code
 *
 * Return: Always 0.
 */
int main(void)
{
    unsigned int n;

    n = binary_to_uint("1");
    printf("%u\n", n);
    n = binary_to_uint("101");
    printf("%u\n", n);
    n = binary_to_uint("1e01");
    printf("%u\n", n);
    n = binary_to_uint("1100010");
    printf("%u\n", n);
    n = binary_to_uint("0000000000000000000110010010");
    printf("%u\n", n);
    return (0);
}
julien@ubuntu:~/0x14. Binary$ gcc -Wall -pedantic -Werror -Wextra -std=gnu89 0-main.c 0-binary_to_uint.c -o a
julien@ubuntu:~/0x14. Binary$ ./a 
1
5
0
98
402
julien@ubuntu:~/0x14. Binary$

1-print_binary.c

Write a function that prints the binary representation of a number.

  • Prototype: void print_binary(unsigned long int n);
  • Format: see example
  • You are not allowed to use arrays
  • You are not allowed to use malloc
  • You are not allowed to use the % or / operators
julien@ubuntu:~/0x14. Binary$ cat 1-main.c 
#include <stdio.h>
#include "main.h"

/**
 * main - check the code
 *
 * Return: Always 0.
 */
int main(void)
{
    print_binary(0);
    printf("\n");
    print_binary(1);
    printf("\n");
    print_binary(98);
    printf("\n");
    print_binary(1024);
    printf("\n");
    print_binary((1 << 10) + 1);
    printf("\n");
    return (0);
}
julien@ubuntu:~/0x14. Binary$ gcc -Wall -pedantic -Werror -Wextra -std=gnu89 1-main.c 1-print_binary.c _putchar.c -o b
julien@ubuntu:~/0x14. Binary$ ./b 
0
1
1100010
10000000000
10000000001
julien@ubuntu:~/0x14. Binary$

2-get_bit.c

Write a function that returns the value of a bit at a given index.

  • Prototype: int get_bit(unsigned long int n, unsigned int index);
  • where index is the index, starting from 0 of the bit you want to get
  • Returns: the value of the bit at index index or -1 if an error occured
julien@ubuntu:~/0x14. Binary$ cat 2-main.c
#include <stdio.h>
#include "main.h"

/**
 * main - check the code
 *
 * Return: Always 0.
 */
int main(void)
{
    int n;

    n = get_bit(1024, 10);
    printf("%d\n", n);
    n = get_bit(98, 1);
    printf("%d\n", n);
    n = get_bit(1024, 0);
    printf("%d\n", n);
    return (0);
}
julien@ubuntu:~/0x14. Binary$ gcc -Wall -pedantic -Werror -Wextra -std=gnu89 2-main.c 2-get_bit.c -o c  
julien@ubuntu:~/0x14. Binary$ ./c
1
1
0
julien@ubuntu:~/0x14. Binary$

3-set_bit.c

Write a function that sets the value of a bit to 1 at a given index.

  • Prototype: int set_bit(unsigned long int *n, unsigned int index);
  • where index is the index, starting from 0 of the bit you want to set
  • Returns: 1 if it worked, or -1 if an error occurred
julien@ubuntu:~/0x14. Binary$ cat 3-main.c
#include <stdio.h>
#include "main.h"

/**
 * main - check the code
 *
 * Return: Always 0.
 */
int main(void)
{
    unsigned long int n;

    n = 1024;
    set_bit(&n, 5);
    printf("%lu\n", n);
    n = 0;
    set_bit(&n, 10);
    printf("%lu\n", n);
    n = 98;
    set_bit(&n, 0);
    printf("%lu\n", n);
    return (0);
}
julien@ubuntu:~/0x14. Binary$ gcc -Wall -pedantic -Werror -Wextra -std=gnu89 3-main.c 3-set_bit.c -o d
julien@ubuntu:~/0x14. Binary$ ./d
1056
1024
99
julien@ubuntu:~/0x14. Binary$

4-clear_bit.c

Write a function that sets the value of a bit to 0 at a given index.

  • Prototype: int clear_bit(unsigned long int *n, unsigned int index);
  • where index is the index, starting from 0 of the bit you want to set
  • Returns: 1 if it worked, or -1 if an error occurred
julien@ubuntu:~/0x14. Binary$ cat 4-main.c
#include <stdio.h>
#include "main.h"

/**
 * main - check the code
 *
 * Return: Always 0.
 */
int main(void)
{
    unsigned long int n;

    n = 1024;
    clear_bit(&n, 10);
    printf("%lu\n", n);
    n = 0;
    clear_bit(&n, 10);
    printf("%lu\n", n);
    n = 98;
    clear_bit(&n, 1);
    printf("%lu\n", n);
    return (0);
}
julien@ubuntu:~/0x14. Binary$ gcc -Wall -pedantic -Werror -Wextra -std=gnu89 4-main.c 4-clear_bit.c -o e
julien@ubuntu:~/0x14. Binary$ ./e
0
0
96
julien@ubuntu:~/0x14. Binary$

5-flip_bits.c

Write a function that returns the number of bits you would need to flip to get from one number to another.

  • Prototype: unsigned int flip_bits(unsigned long int n, unsigned long int m);
  • You are not allowed to use the % or / operators
julien@ubuntu:~/0x14. Binary$ cat 5-main.c
#include <stdio.h>
#include "main.h"

/**
 * main - check the code
 *
 * Return: Always 0.
 */
int main(void)
{
    unsigned int n;

    n = flip_bits(1024, 1);
    printf("%u\n", n);
    n = flip_bits(402, 98);
    printf("%u\n", n);
    n = flip_bits(1024, 3);
    printf("%u\n", n);
    n = flip_bits(1024, 1025);
    printf("%u\n", n);
    return (0);
}
julien@ubuntu:~/0x14. Binary$ gcc -Wall -pedantic -Werror -Wextra -std=gnu89 5-main.c 5-flip_bits.c -o f
julien@ubuntu:~/0x14. Binary$ ./f
2
5
3
1
julien@ubuntu:~/0x14. Binary$

100-get_endianness.c

Write a function that checks the endianness.

  • Prototype: int get_endianness(void);
  • Returns: 0 if big endian, 1 if little endian
julien@ubuntu:~/0x14. Binary$ cat 100-main.c
#include <stdio.h>
#include "main.h"

int main(void)
{
    int n;

    n = get_endianness();
    if (n != 0)
    {
        printf("Little Endian\n");
    }
    else
    {
        printf("Big Endian\n");
    }
    return (0);
}
julien@ubuntu:~/0x14. Binary$ gcc -Wall -pedantic -Werror -Wextra -std=gnu89 100-main.c 100-get_endianness.c -o h
julien@ubuntu:~/0x14. Binary$ ./h 
Little Endian
julien@ubuntu:~/0x14. Binary$ lscpu | head
Architecture:          x86_64
CPU op-mode(s):        32-bit, 64-bit
Byte Order:            Little Endian
CPU(s):                1
On-line CPU(s) list:   0
Thread(s) per core:    1
Core(s) per socket:    1
Socket(s):             1
NUMA node(s):          1
Vendor ID:             GenuineIntel
julien@ubuntu:~/0x14. Binary$

101-password

Find the password for this program.

Save the password in the file 101-password Your file should contain the exact password, no new line, no extra space

julien@ubuntu:~/0x14. Binary$ ./crackme3 `cat 101-password`
Congratulations!
julien@ubuntu:~/0x14. Binary$