Introduction

This category shows training exercises about C language. For all questions, please ask on the BackToBasics’ Discord server.

We cannot use the intranet, so there are somes given files. Please play the game and do not read the test file. You can download it here.

A Makefile is already given with these rules:

  • basics: compiles ;
  • debug: compiles with debug flags ;
  • check: runs the testsuite ;
  • clean: removes all trash files.

You are only allowed to uses the functions defined in the following headers:

  • stdio.h

All of the code must be done inside a basics.c file.

Your code must compile with the following flags: -std=c99 -pedantic -Wall -Wextra -Werror -Wvla.

Your code must not segfault and have any memory leak.

FizzBuzz

Goal

You have to implement the following function:

void fizzbuzz(int n);

This function displays on stdout the numbers from 1 to n with newlines. However, it must follow the rules:

  • for multiples of 3, it should print “Fizz” with a newline ;
  • for multiples of 5, it should print “Buzz” with a newline ;
  • for multiples of 3 and of 5, it should print “FizzBuzz” with a newline.

Example

The output of fizzbuzz(5) is:

1
2
Fizz
4
Buzz

My strlen

You have to implement the following function:

size_t my_strlen(char *s);

This functions returns the length of the string argument. The string can be null, and its size will be 0.

Binary number

You have to implement the following function:

long binary_number(char str[]);

This function returns the integer in decimal corresponding to the binary number given in argument. If a caracter does not correspond to a binary digit, return -1.

Example

The output of binary_number("110") is 6.

The output of binary_number("This is not correct") is -1.

Hamming Distance DNA

You have to implement the following function:

int hamming_distance(char *dna1, char *dna2);

This function returns the number of differents characters between the two strings given in arguments.

We read DNA using the letters C,A,G and T. If there is another caracter than the previous one, return -1. Moreover, if the size of the two parameters are not equal, return -1.

Example

The output of hamming_distance("CAGT", "GAGT") is 1.

Isogram

You have to implement the follwing function:

int is_isogram(char *s);

This function returns if the given string is an isogram. An isogram word or sentence is a word or a phrase without a repetiting letter, however spaces and non letter caracters are allowed to appear multiple times.

Example

House is an isogram word, but Test. is not.

Move Robot

You have to implement the following function:

struct pair move_robot(struct pair current, char *directions);

Moreover, you have to implement the pair structure with two integer: x and y.

This function moves a robot in the current coordinates on a grid from a string of directions and returns the new coordinates of the robot.

The string of directions corresponds to a string of operations done on the robot:

  • U for up ;
  • L for left ;
  • D for down ;
  • R for right.

Example

The output of move_robot({1, 1}, "UL") is the structure pair {0, 2}.