Strings

String

A string is an array of characters, that is terminated by a null character \0 (ASCII value of zero). 7 To convert an array of characters into a string, add a null character '\0 at the end of the array. String functions then can be used to manipulate these strings (<string.h>).

Declaration, Assignment, Initialisation

char str[];

When assigning characters to the array, the array must have the null character \0.

Initialising can be done in two ways:

• through initialising a character array char str[] = {'o', 'k', '\0')
• through assigning a string (no null character needed) char str[] = "ok"

Input/Output

Input:

• fgets (str, size, stdin) reads char, or until newline
• scanf ("%s", str) reads until whitespace

Output:

• puts(str) terminates with newline
• printf("%s\n", str)
• fgets reads in newline character, so replacement of \n for \0 may be necessary

String Functions

• strlen(s) Returns number of characters in
• strcmp(s1, s2) Compares ASCII values of the corresponding characters in s1, s2
• strncmp(s1, s2, n) Compare first characters of s1, s2
• strcpy(s1, s2) Copies string pointed to by s2 into array pointed to by s1.
• strncpy(s1, s2, n) Copies first characters pointed to by s2 to s1.