0x0F-function_pointers

0x0F. C - Function pointers

Resources

Read or watch:

• Function Pointer in C
• Pointers to functions
• Function Pointers in C / C++
• why pointers to functions?
• Everything you need to know about pointers in C

Learning Objectives

General

• What are function pointers and how to use them
• What does a function pointer exactly hold
• Where does a function pointer point to in the virtual memory

Tasks

0. What's my name

• Write a function that prints a name.

Requirements:

Prototype: void print_name(char *name, void (*f)(char *));

Mode: mandatory

File: 0-print_name.c

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1. If you spend too much time thinking about a thing, you'll never get it done

• Write a function that executes a function given as a parameter on each element of an array.

Requirements:

Prototype: void array_iterator(int *array, size_t size, void (*action)( int)); where size is the size of the array and action is a pointer to the function you need to use

Mode: mandatory

File: 1-array_iterator.c

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2. To hell with circumstances; I create opportunities

• Write a function that searches for an integer.

Requirements:

Prototype: int int_index(int *array, int size, int (*cmp)(int)); where size is the number of elements in the array array cmp is a pointer to the function to be used to compare values int_index returns the index of the first element for which the cmp function does not return 0 If no element matches, return -1 If size <= 0, return -1

Mode: mandatory

File: 2-int_index.c

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3. A goal is not always meant to be reached, it often serves simply as something to aim at

• Write a program that performs simple operations.

Requirements:

You are allowed to use the standard library Usage: calc num1 operator num2 You can assume num1 and num2 are integers, so use the atoi function to convert them from the string input to int operator is one of the following:

+: addition -: subtraction *: multiplication /: division %: modulo

+: addition -: subtraction *: multiplication /: division %: modulo The program prints the result of the operation, followed by a new line You can assume that the result of all operations can be stored in an int if the number of arguments is wrong, print Error, followed by a new line, and exit with the status 98 if the operator is none of the above, print Error, followed by a new line, and exit with the status 99 if the user tries to divide (/ or %) by 0, print Error, followed by a new line, and exit with the status 100

Mode: mandatory

File: 3-main.c, 3-op_functions.c, 3-get_op_func.c, 3-calc.h

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4. Most hackers are young because young people tend to be adaptable. As long as you remain adaptable, you can always be a good hacker

• Write a program that prints the opcodes of its own main function.

Requirements:

Usage: ./main number_of_bytes Output format:

the opcodes should be printed in hexadecimal, lowercase each opcode is two char long listing ends with a new line see example

the opcodes should be printed in hexadecimal, lowercase each opcode is two char long listing ends with a new line see example You are allowed to use printf and atoi You have to use atoi to convert the argument to an int If the number of argument is not the correct one, print Error, followed by a new line, and exit with the status 1 If the number of bytes is negative, print Error, followed by a new line, and exit with the status 2 You do not have to compile with any flags

Mode: #advanced

File: 100-main_opcodes.c

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