C Arrays of Strings

Arrays of Strings

A string is an array of characters. When you want to store a list of words, like names or fruits, you can use an array of strings.

In C, an array of strings is a two-dimensional array of characters:

char fruits[3][10] = {"Apple", "Banana", "Cherry"};

printf("%s\n", fruits[0]);

The first number (3) is how many strings the array can hold. The second number (10) is the size of each string, including the \0 at the end (see The Null Character). So each fruit can have up to 9 letters.

You can think of it as a table, where each row is one string:

Loop Through an Array of Strings

Use a for loop to print all the strings in the array:

char fruits[3][10] = {"Apple", "Banana", "Cherry"};
int i;

for (i = 0; i < 3; i++) {
  printf("%s\n", fruits[i]);
}

Note: Do not use strlen() here. It counts the characters in one string, not the number of strings.

To get the number of strings, use sizeof(fruits) / sizeof(fruits[0]) (30 / 10 = 3):

char fruits[3][10] = {"Apple", "Banana", "Cherry"};
int count = sizeof(fruits) / sizeof(fruits[0]);
int i;

printf("Number of strings: %d\n", count);

for (i = 0; i < count; i++) {
  printf("%s\n", fruits[i]);
}

Access a Single Character

To access one character, use two indexes: the first one picks the string, and the second one picks the character in that string.

For example, fruits[1][0] is the first character of the second string:

char fruits[3][10] = {"Apple", "Banana", "Cherry"};

printf("%c\n", fruits[1][0]);  // B

Change a String

You cannot use = to give a string in the array a new value:

fruits[0] = "Mango";  // Error

Use the strcpy() function instead (see String Functions):

char fruits[3][10] = {"Apple", "Banana", "Cherry"};

strcpy(fruits[0], "Mango");
printf("%s\n", fruits[0]);

Note: The new string must fit in the row. "Mango" needs 6 characters (5 letters and \0), so it fits in 10. "Watermelon" needs 11, so it does not.

Real-Life Example

Check if a name is on a guest list. In this example, we check if "Jenny" is on the list.

The program compares the name with each string in the array, using strcmp().

It returns 0 when two strings are equal:

char guests[4][20] = {"Liam", "Anja", "Jenny", "Olivia"};
char name[] = "Jenny";
int found = 0;
int i;

for (i = 0; i < 4; i++) {
  if (strcmp(guests[i], name) == 0) {
    found = 1;
    break;
  }
}

if (found) {
  printf("%s is on the guest list\n", name);
} else {
  printf("%s is not on the guest list\n", name);
}