Strings

Strings are character sequences that are either expressed in double quotes or as arrays that end with a null character '\0'.

Syntax

char string-name[];
char string_name[] = "abcd";
char string_name[size] = {'a', 'b', 'c', 'd', '\0'};

Strings in C are first declared with the char data type, followed by the string_name, and then immediately followed by square brackets []. The snippet above showcases the two ways that string values are initialized:

• Zero or more characters, digits, and escape sequences surrounded in double quotes.
• An array of comma-separated characters, surrounded in curly brackets { }, and ending with a null character '\0'*.

* This is required when an optional size is passed to square brackets to specify the number of characters in the string.

Example

The following declaration and initialization create a string of "Howdy":

char message[6] = {'H', 'o', 'w', 'd', 'y', '\0'};

Even though "Howdy" has only 5 characters, message has 6 characters due to the null character at the end of the message array.

The above statement can be rewritten as:

char message[] = "Howdy";

Memory

Here’s the memory presentation:

Character |   'H'    'o'    'w'    'd'    'y'   '\0'
Index     |    0      1      2      3      4      5
Address   |  23451  23452  23453  23454  23455  23456

Displaying a String

To display a string in C, the printf() function from the stdio.h header file can be used along with the %s character to format strings, followed by the string name.

Display Example

The following is an example of displaying a string in C:

#include <stdio.h>

int main() {
  char message[] = "Hi y'all!";
  printf("Bot: %s\n", message);

  return 0;
}

The output would be:

Bot: Hi y'all!

String Functions

The string.h header defines a handful of string functions for manipulating arrays of characters.