Working with Files in the C Programming Language, Practical Examples and Tips for Efficient Programming

Working with files in the C programming language represents a key functionality that enables programmers to write, read, and manipulate data that is permanently stored on disk. This capability is essential for developing applications that require data storage between program executions, such as databases, configuration files, or logs. In the C programming language, file operations are achieved using the standard <stdio.h> library, which provides functions for opening, reading, writing, and closing files. In the C programming language, files are treated as data streams. There are two basic types of files:

• Text files – data is stored as a sequence of characters, often human-readable, such as .txt files.
• Binary files – data is stored in binary format, which is more efficient for machine processing, such as images, executable files, etc.

The FILE data type, defined in <stdio.h>, is used for working with files. This type is actually a pointer to a structure that contains information about the file, such as its location, current pointer position, and operating mode.

Working with files is straightforward in C programming

The C standard library provides several functions for working with files, including:

fopen() - Opens a file. 

fclose() - Closes a file.

fprintf() - Writes formatted text to a file.

fscanf() - Reads formatted text from a file.

fputc() - Writes a single character to a file.

fgetc() - Reads a single character from a file.

fwrite() - Writes a block of bytes to a file.

fread() - Reads a block of bytes from a file.

Working with files in the C programming language provides a powerful tool for data management, but requires attention to resource handling and error checking. Through the standard library, programmers can efficiently implement functionalities for both text and binary files, with flexibility for various types of applications. With basic operations such as opening, reading, writing, and closing, the C programming language also enables advanced techniques such as positioning and binary data processing, making it suitable for a wide range of tasks. Understanding basic operations such as opening, reading, writing, and closing files is crucial for developing applications that handle large amounts of data. First, we will focus on and examine C code for working with text files.

Reading and Writing Text Files in C Programming

How to Improve Code Readability, User-Defined Types in the C Programming Language

In the C programming language, in addition to basic data types such as int, float, char, etc., you can define your own data types. These user-defined types allow programmers to create more complex data structures that meet the specific needs of their applications. User-defined types in the C programming language: struct, union, enum and typedef, provide programmers with tools to create customized and meaningful data types. Structures are ideal for grouping data, unions for saving memory, enumerations for defining constants, and typedef for simplifying syntax.

Their proper use makes the code more modular, easier to understand and adapt, which is especially important in larger projects. These mechanisms are the foundation for working with complex data in the C programming language and are often used in system programming, database work, and algorithm implementation, while at the same time these user-defined types make the code more readable, organized, and easier to maintain. In addition to user-defined data types, at the end of the lesson, we will also focus on constants in the C programming language.

You need to have a solid understanding of the C programming language to effectively use user-defined types

First of all, we will start with structures because structures are the most commonly used user-defined data types in the C programming language. Structures are user-defined data types that allow grouping different types of data under a single name. They simply enable the combination of different data types into one entity. Each variable within a structure is called a member of the structure. Structures are defined using the struct keyword. A structure is useful when we want to model an entity that has multiple attributes, such as a person, a car, or a point in space.

As we know, the C programming language was developed by Dennis Ritchie at Bell Labs during the early 1970s, and it is based on the earlier programming language B, which was created by Ken Thompson and Ritchie. The B programming language, at that time, around 1970, was simple and did not have structures as a formal concept. Instead, programmers manually managed memory and grouped data using pointers and manual memory offsets. However, Ritchie recognized the need for a higher level of abstraction to make programming more efficient. This means that structures did not exist in the earliest predecessors of the C programming language, but they were introduced very early in its development, practically with the creation of the C programming language as we know it today.

Designing Complex Data Structures in C: Best Practices

Efficient Code Repetition, Using Loops in C Programming

Loops can be described as key elements in programming, enabling the repetition of certain blocks of code while a condition is met. Most modern programmers couldn't imagine coding without loops. However, if you were to go back to 1972, in the earliest versions of the BASIC language, loops as we know them today did not exist in a structured form, and programmers relied on commands like GOTO or jump to control the program flow, including simulating loops. This was characteristic of the first iterations of BASIC, which was designed in 1964 by John Kemeny and Thomas Kurtz at Dartmouth College, with the goal of being simple for beginners.

However, was the GOTO command alone sufficient? Theoretically, the GOTO command is sufficient to simulate any loop because it is a Turing-complete mechanism – any control structure can be expressed with jumps and conditions. However, in practice, it was inefficient and prone to errors. That's why loops were introduced as a response to criticism, including Edsger Dijkstra's famous 1968 article, 'Go To Statement Considered Harmful,' which pointed out the problems of unstructured code.

In the C programming language, the loops: for, while, and do-while, existed from the very beginning, that is, from its creation in 1972, when Dennis Ritchie developed it at Bell Labs. The C programming language was designed as a successor to the B programming language, which itself was a simplified version of BCPL, and one of the goals was to provide a higher level of program flow control compared to its predecessors, while maintaining closeness to machine code.

Loops have always existed in the C programming language

Loops were an integral part of that design, so there was no moment in the history of the standard C programming language where they were absent. Unlike BASIC, which initially relied only on GOTO, the C programming language was designed with loops as a standard tool, inspired by higher-level languages like ALGOL, but adapted for low-level efficiency.

for: For iterations with a known number of repetitions.

while: For conditional loops where the condition is checked before execution.

do-while: For conditional loops where the condition is checked after execution.

In early versions, variable declaration within the for loop header was not allowed; variables had to be declared outside the loop. This changed with the C99 standard, which introduced block scope. With the ANSI C standard in 1989, known as C89/C90, loops were formally defined and have not undergone significant changes in later standards C99, C11, C17, and C23. All three loops have remained consistent in syntax and semantics, showing that Ritchie's design was robust from the very start.

Why Doesn't the C Programming Language Have a 'foreach' Loop, While C++ Has an Alternative?

The Guide to Control Structures If, If-Else, and Switch-Case in C Programming

In the C programming language, control structures such as if, if-else, and else allow programmers to make decisions during program execution. These structures are used to branch the flow of execution based on specific conditions. In programming, control structures enable the management of program execution flow. They determine which parts of the code will be executed and under what conditions. By using if, if-else, and if-else if-else structures, programmers can write flexible programs that make decisions based on various conditions. Proper use of these control structures enables efficient management of the program execution flow and increases code readability.

if statement

The if statement is used to check a specific condition. If the condition is true, the block of code within the if statement is executed. If the condition is not true, that block of code is skipped, and the program continues. if statements can be nested, meaning you can have another if within one if block.

if (condition) {

    // Executes if condition is true

}

Decision statements determine the flow of the program

if-else statement

The if-else statement extends if by adding an alternative block of code that is executed if the condition is not met. This allows the program to choose between two possibilities.

if (condition1) {

    // Executes if condition is true

} else {

    // Executes if none of the conditions are true

}

if-else if- else statement

When it is necessary to check multiple conditions, a combination of if with one or more else if parts, with an optional final else, is used. This allows the program to branch into multiple possible outcomes.

 

if (condition1) {

    // Executes if condition1 is true

} else if (condition2) {

    // Executes if condition1 is false and condition2 is true

} else {

    // Executes if none of the conditions are true

}

What Are the Differences in If Statements Between the C Programming Language and Others?

Practical Examples of Using Operators in the C Programming Language

In the C programming language, operators are symbols that enable the execution of specific operations on data, such as mathematical calculations, logical comparisons, or bit manipulations. Operators are symbols that instruct the compiler what to do with operands in an expression. Understanding operators is crucial for writing efficient and effective code. The C programming language is known for its simplicity and direct hardware control, which is reflected in its set of operators. C programming language operators reflect its low-level and efficiency philosophy. Unlike higher-level languages such as Python or JavaScript, the C programming language does not have operators for advanced functionalities like exponentiation ** in the Python programming language because it focuses on simplicity and control. Bitwise and pointer operators make the C programming language powerful for system programs, while the lack of logical types or automatic memory management requires greater programmer attention compared to modern languages. Essentially, C programming language operators are the foundation for many other languages, but their directness and minimalism remain unique.

Operators in the C programming language require deeper knowledge

The C programming language supports a wide range of operators used for various data operations. Each operator has its own specific behavior and rules of application, which allows programmers to manipulate data in various ways and execute complex operations. Correct use of operators can significantly improve code performance and readability. Operators in C programming language can be categorized into several types:

• Arithmetic Operators

• Assignment Operator

• Compound Assignment Operators

• Relational (Comparison) Operators

• Logical Operators

• Bitwise Operators

• Unary Operators

• Ternary Operators

• Pointer Operators

• Size and Type Operators

• Etc.

Basic Arithmetic Operators in the C Programming Language: Everything You Need to Know

How to Use Derived Data Types in C Programming Language for Efficient Programming

In the C programming language, in addition to basic data types such as int, float, char, and double, there are derived data types that are based on basic types, but offer additional capabilities and flexibility when working with data. Derived data types are types that extend the functionality of primitive types by combining or referencing existing data. They allow the programmer to efficiently manage memory, group data, or define operations. Unlike primitive types, which directly store values, derived types often involve indirection, such as pointers, or the organization of multiple elements, such as arrays.

The main derived data types in the C language are:

Pointers: A data type that stores a memory address, e.g., int*, char* 

 

Arrays: A collection of elements of the same type, e.g., int arr [10]

 

Functions: The return value type of a function, e.g., int function ())

As you can see, in the C programming language, the main derived data types are pointers, arrays, and functions, and user-defined types such as struct, union, and enum are often implicitly included in this category, although they are formally different. We will write about user-defined types in the next blog post. Now we will concentrate only on derived data types that are not user-defined. If you are wondering how functions are a derived data type, then you simply need to know that functions in the C programming language have a type defined by their return value. They are not variables in the classical sense, but they are considered derived types because they allow defining operations on data. We hope this has cleared up any confusion. If anything is unclear, ask in the comments or contact us personally via the contact form on our blog.

A software engineer is considering using derived data types in the C programming language

Pointers are one of the most powerful and characteristic aspects of the C language. They store the address in memory where the data is located, instead of the value itself. This allows for indirect access to data and dynamic memory allocation. Pointers in the C programming language are one of the key elements that make C so flexible and close to hardware. They are both fascinating and challenging, as they allow direct manipulation of memory, but their proper use can significantly improve program performance, while careless handling can lead to problems such as memory leaks and default errors. With pointers, you must code carefully and think carefully about when and how to use them.

Pointer Declaration:

int *ptr;

This means that ptr is a pointer to an integer value, int type specifies the type of data the pointer points to e.g., int, float, char, while * indicates that this is a pointer.

Key Operators:

& Address-of Operator - Retrieves the memory address of a variable.

* Dereference Operator - Accesses or modifies the value at the address stored in the pointer.

          Initialization Example:

int number = 10;

int *ptr = &number; // ptr points to the address of the number variable

Pointer Dereferencing:

    printf("Value at address: %d\n", *ptr); // Prints 10 

Dereferencing means accessing the value at the address that the pointer points to. Arrays in the C programming language are actually pointers to the first element. You can use them to traverse the array. Pointers can be used to pass arguments to functions to allow modifications of the original values. Function pointers allow functions to be called dynamically, based on their address. A pointer can also point to another pointer, allowing multiple levels of indirection. In any case, you will master pointers most easily through practice and coding.

Understanding and Applying Pointers in a Practical Example in C Programming Language

Understanding Primitive Data Types in the C Programming Language

C is a statically typed programming language, which means that every variable must have a clearly defined type. Data types in C determine the amount of memory that a variable occupies, as well as the operations that can be performed on it. Simply put, in the C programming language, data types refer to things that are separate entities in other programming languages. That's why we'll learn them all at once. Just keep in mind that many things in the C programming language are limited and don't even have what the C++ programming language has, let alone what we can tell you about other more modern programming languages. There are four main categories of data types in C:

• Basic or primitive data types

• Certain type modifiers

• Complex data types

• User-defined types

Primitive types in C are simple, close to the hardware, and flexible, but less standardized compared to modern languages. C++ extends them with better tools e.g. bool, <cstdint>, while languages like Java and Python introduce a higher level of abstraction and standardization. If you're programming in C, it's important to understand the platform you're working on because it affects the behavior of these types.

Data types in the C programming language work differently compared to more modern programming languages

Let's take a look at the first category of data types. Here's an overview of the basic or primitive data types in C:

Integers - Integer Types:

int - Used for whole numbers (e.g. 5, -10, 42). The size depends on the system architecture (usually 4 bytes on 32-bit or 64-bit systems).

short - A shorter integer (usually 2 bytes).

long - A longer integer (4 or 8 bytes, depending on the system).

long long - An even longer integer (at least 8 bytes, introduced in C99).

Modifiers:

signed - Allows positive and negative values (the default for int).

unsigned - Allows only non-negative values, which doubles the positive range (e.g. unsigned int).

Floating-Point Numbers - Floating-Point Types:

float - Single precision (usually 4 bytes), for decimal numbers (e.g. 3.14).

double - Double precision (usually 8 bytes), for greater accuracy of decimal numbers.

long double - Extended precision (size depends on the system, often 10, 12 or 16 bytes).

Characters - Character Type:

char - A single character (e.g. 'A', 'b') or a small integer (1 byte).

signed char - From -128 to 127.

unsigned char - From 0 to 255.

Logical Type - Boolean:

In standard C before C99, there was no special type, but since C99, _Bool is introduced, 0 for false, 1 for true. With the <stdbool.h> library, bool can be used as an alias for _Bool, along with true and false.

Empty Type - Void:

void - Indicates the absence of a type. It is used in functions that do not return a value or in pointers to an undefined data type void*.

Why Are Primitive Types in C Close to Hardware and How Does This Differ from Other Languages?