Arrays and Strings in C Programming

Key Terms:

• Element: An individual value stored in an array.
• Index: Position number of an element in the array, starting from 0.
• Contiguous Memory: Array elements are stored one after another in memory.

int numbers[5] = {10, 20, 30, 40, 50};
printf("%d\n", numbers[2]);  // Outputs 30

Key Terms:

• Character: A single letter, digit, or symbol stored in a char variable.
• Null Character ('\0'): A special character indicating the end of a string.

char name[] = "Rahul";
printf("%s\n", name);  // Outputs Rahul

How to Work with Arrays and Strings?

• Accessing elements: Use indexes starting at 0, like array[0] for the first element.
• Modifying elements: Assign new values to specific indexes, e.g., numbers[1] = 25;
• Looping through arrays: Use loops like for or while to process elements.
• String functions: Use built-in functions like strlen(), strcpy(), strcmp() from string.h to work with strings.

int i;
int numbers[5] = {10, 20, 30, 40, 50};
for (i = 0; i < 5; i++) {
    printf("Element %d: %d\n", i, numbers[i]);
}

Common Operations with Strings

• strlen(str) – Returns the length of the string (excluding '\0').
• strcpy(dest, src) – Copies the source string into the destination.
• strcmp(str1, str2) – Compares two strings and returns 0 if they are equal.
• strcat(dest, src) – Concatenates (appends) the source string to the destination string.

Practice Assignments

1. Declare an integer array of size 10, initialize it with values, and print all elements.
2. Write a program that reads a string from the user and prints its length using strlen().
3. Write a program to reverse a string entered by the user.
4. Write a program to concatenate two strings using strcat().

Further Reading