CS25C01 Unit IV IN C | Strings and Pointers in C Explained
CS25C01 Unit IV IN C:
Strings & Pointers: One-dimensional and Multi-dimensional Arrays, Array operations and traversals,String Handling: String declaration, input/output, string library functions, Pointer arithmetic, Pointers and Arrays, Pointers to function, Dynamic memory allocation.
CS25C01 Unit IV IN C:
Unit IV of the Anna University C programming syllabus is where students move from basic programming to working with data in memory. It covers arrays, strings, pointers, function pointers and dynamic memory allocation. These topics look difficult at first, but they are the foundation of how C works, and they carry over into data structures, operating systems and embedded programming. Understanding this unit well also makes it easier to score in the exam, because many 10-mark programs come from it.
The unit begins with arrays, which store many values of the same type under a single name. A one-dimensional array is a simple list, such as marks of five students, accessed with an index starting from zero. A multi-dimensional array, such as a two-dimensional matrix, stores data in rows and columns and is kept in memory row by row. Students learn the common array operations: traversal, insertion, deletion, searching, sorting and finding the largest or smallest element. Matrix addition and multiplication are favourite exam programs, so practise them with nested loops.
Next comes string handling. In C, a string is a character array that ends with the null character '\0'. You learn to declare strings, read them with scanf or fgets, and print them with printf or puts. The <string.h> library gives useful functions such as strlen for length, strcpy for copying, strcat for joining, strcmp for comparing and strstr for finding a substring. Programs like checking a palindrome, reversing a string and counting vowels are asked again and again, so they are worth practising by hand. A good tip is to avoid gets(), because it has no limit on input size and is considered unsafe.
Pointers are the heart of this unit. A pointer is a variable that stores the address of another variable, and the * operator lets you reach the value stored at that address. Pointer arithmetic means that p++ moves the pointer by the size of its data type, so it jumps to the next element of an array. This is why pointers and arrays are so closely linked: a[i] and *(a+i) mean exactly the same thing. The unit also introduces pointers to functions, written as int (*fp)(int, int), which let a program choose which function to call while it is running. They are used in menu-driven programs and callbacks.
The unit ends with dynamic memory allocation, which lets a program request memory while it runs instead of fixing the size in advance. The four key functions are malloc to allocate memory, calloc to allocate and set it to zero, realloc to resize a block and free to release it. Always check whether the returned pointer is NULL, and always free memory you no longer need, otherwise you create a memory leak. To prepare, write each program yourself, trace the output on paper, and revise the difference between malloc and calloc, which is a frequent 2-mark question. With regular practice, Unit IV can become one of your strongest units in the exam.
If you would like, I can also write this in Tamil for your blog, add an SEO title and meta description, or create a separate post with the important programs and solutions.
UNIT 4 NOTES DOWNLOAD LINK:-
https://drive.google.com/file/d/10ZNspPxNM8IH8stHxzxEyWYOrz1ii7Qt/view?usp=sharing