**Course Title:** Mastering C: From Fundamentals to Advanced Programming **Section Title:** Arrays and Strings **Topic:** Create programs that manipulate arrays and strings. (Lab topic) **Introduction:** In this lab topic, we will explore how to create programs that manipulate arrays and strings in C. We will cover various techniques for working with arrays and strings, including sorting, searching, and concatenating. By the end of this topic, you will have a solid understanding of how to write efficient and effective C programs that handle arrays and strings. **Sorting and Searching Arrays:** Sorting and searching are two common operations that are often used to manipulate arrays. In C, there are several built-in functions that can be used for sorting and searching arrays, including: * qsort(): A function that sorts an array in ascending or descending order. * bsearch(): A function that searches for a value in a sorted array. Here is an example program that uses the qsort() function to sort an array: ```c #include <stdio.h> #include <stdlib.h> // Define a function to compare two integers int compare(const void *a, const void *b) { return (*(int*)a - *(int*)b); } int main() { int array[] = {64, 34, 25, 12, 22, 11, 90}; int n = sizeof(array) / sizeof(array[0]); printf("Original array: "); for (int i = 0; i < n; i++) { printf("%d ", array[i]); } printf("\n"); qsort(array, n, sizeof(int), compare); printf("Sorted array: "); for (int i = 0; i < n; i++) { printf("%d ", array[i]); } printf("\n"); return 0; } ``` This program uses the qsort() function to sort an array of integers in ascending order. The compare() function is used to compare two integers and determine their order. **String Manipulation:** In C, there are several built-in functions that can be used to manipulate strings, including: * strcat(): A function that concatenates two strings. * strcpy(): A function that copies one string to another. * strcmp(): A function that compares two strings. Here is an example program that uses the strcat() function to concatenate two strings: ```c #include <stdio.h> #include <string.h> int main() { char str1[100] = "Hello"; char str2[] = " World"; strcat(str1, str2); printf("Concatenated string: %s\n", str1); return 0; } ``` This program uses the strcat() function to concatenate two strings and store the result in the first string. **Passing Arrays to Functions:** In C, arrays can be passed to functions in several ways: * Passing the array itself. * Passing a pointer to the array. * Passing a reference to the array. Here is an example program that passes an array to a function: ```c #include <stdio.h> void printArray(int array[], int n) { for (int i = 0; i < n; i++) { printf("%d ", array[i]); } printf("\n"); } int main() { int array[] = {1, 2, 3, 4, 5}; int n = sizeof(array) / sizeof(array[0]); printArray(array, n); return 0; } ``` This program passes an array to a function called printArray(), which prints the elements of the array. **Lab Exercises:** 1. Write a program that uses the qsort() function to sort an array of integers in descending order. 2. Write a program that uses the strcat() function to concatenate three strings and store the result in the first string. 3. Write a program that passes a 2D array to a function and prints the elements of the array. **Conclusion:** In this lab topic, we explored how to create programs that manipulate arrays and strings in C. We covered various techniques for working with arrays and strings, including sorting, searching, and concatenating. By the end of this topic, you should have a solid understanding of how to write efficient and effective C programs that handle arrays and strings. **Note:** Please try the lab exercises on your own before checking the solutions. If you have any questions or need help, feel free to ask in the comments section below. **References:** * C Standard Library: [https://www.tutorialspoint.com/c_standard_library/index.htm](https://www.tutorialspoint.com/c_standard_library/index.htm) * String functions in C: [https://www.geeksforgeeks.org/string-functions-in-c/](https://www.geeksforgeeks.org/string-functions-in-c/) * Array manipulation in C: [https://www.tutorialspoint.com/cprogramming/index.htm](https://www.tutorialspoint.com/cprogramming/index.htm) **Next Topic:** Understanding pointers: declaration, initialization, and dereferencing. (Pointers and Memory Management)