Introduction

<aside> 💡 C Strings There is no built-in C string type. The “convention” is that a C string is an array of characters, terminated by a null character.

</aside>

The null character (terminator)

We use \\0 which is also equivalent to 0, to denote the null character.

(Note that it is very different from 0!)

strlen

The string library (#include <string.h>) provides many useful functions, strlen is one of them.

It returns the length of the string (not necessarily the length of the array)

Note that the time complexity for strlen is O(n)!!

strcmp

It compares two string using a lexicographical order

• If s1 === s2, it returns zero
• If s1 < s2, it returns a negative integer
• If s1 > s2, it returns a positive integer

An interesting way of implementation it!

// my_strcmp(s1, s2) behaves the same as strcmp and returns:
//   s1 preceeds s2      => negative int
//   s1 identical to s2  => 0
//   s1 follows s2       => positive int
// time: O(n), n is min of the lengths of s1, s2
int my_strcmp(const char s1[], const char s2[]) {
  assert(s1);
  assert(s2);
  int i = 0;
  while (s1[i] == s2[i] && s1[i]) {
    ++i;
  }
  return s1[i] - s2[i];
}