C Strings

Creating a String

The easiest way to make a string is to use a char array and assign it a value in double quotes. C automatically adds the null terminator at the end, so you do not have to write it yourself.

#include <stdio.h>

int main() {
  char greeting[] = "Hello";
  printf("%s\n", greeting);
  return 0;
}

Strings Are Character Arrays

Because a string is really an array, you can reach individual letters using an index, exactly like any other array. The word Hello uses indexes 0 through 4, and index 5 holds the null terminator.

#include <stdio.h>

int main() {
  char greeting[] = "Hello";
  printf("First letter: %c\n", greeting[0]);
  greeting[0] = 'J';
  printf("Now it says: %s\n", greeting);
  return 0;
}

Looping Through a String

You can walk through a string one character at a time with a loop. A common trick is to keep going until you hit the null terminator, which marks the true end of the text.

#include <stdio.h>

int main() {
  char word[] = "Code";
  for (int i = 0; word[i] != '\0'; i++) {
    printf("%c\n", word[i]);
  }
  return 0;
}