README.md

0x14. C - Bit manipulation

Learning objectives:

• Look for the right source of information without too much help
• How to manipulate bits and use bitwise operators

Tasks:

• 0. 0

  • 0-binary_to_uint.c: C program 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

• 1. 1

  • 1-print_binary.c: C program that prints the binary representation of a number
    • Prototype: void print_binary(unsigned long int n);
    • arrays are not allowed
    • malloc is not allowed
    • % or / operators are not allowed

• 2. 10

  • 2-get_bit.c: C program 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
    • Return: the value of the bit at index index or -1 if an error occurred

• 3. 11

  • 3-set_bit.c: C program 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
    • Return: 1 if it worked, or -1 if an error occurred

• 4. 100

  • 4-clear_bit.c: C program that sets the value of a bit to 0 at a given index
    • Prototype: int clear_bit(unsigned int *n, unsigned int index);
    • where index is the index, starting from 0 of the bit you want to set
    • Return: 1 if it worked, or -1 if an error occurred

• 5. 101

  • 5-flip_bits.c: C program 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);
    • % or / operators are not allowed

• 6. Endianness

  • 100-get_endianness.c: C program that checks the endianness
    • Prototype: int get_endianness(void);
    • Return: 0 if big endian, 1 if little endian

• 7. Crackme3

  • 101-password: Password to task 7