C Made Easy: A Beginner's Guide to Programming Basics

Introduction

C is a powerful programming language that is widely used to create operating systems , embedded systems and high-performance applications. This guide will take you on a journey into C programming, starting with the basics and walking you step-by-step through its key concepts.

Install the C compiler

Before you begin, you need to install the C compiler. The following options are recommended:

• GNU C Compiler (GCC): for Linux, macOS, and Windows
• Microsoft Visual C: for Windows
• Clang: Available on macOS and Linux

Create your first C program

Let's start with a simple "Hello, world!" program:

#include 

int main() {
    printf("你好，世界！\n");
    return 0;
}

Understanding C code

#include : This is a preprocessor directive that includes the standard input/output library and allows you to use printf() function.

int main(): This is the entry point of the program, it defines the main function.

printf("Hello, world!\n"): The printf() function is used to output text to the screen.

return 0;: This is the return value of the main function, which indicates successful execution of the program.

data type

C has various data types to represent different data values:

• int: Integer
• float: floating point number
• char: single character
• double: double floating point number

Variables and Constants

• Variables: Named location where data is stored.
• Constant: Value that cannot be changed.

Use the const keyword to declare constants, for example:

const int MY_CONSTANT = 10;

Control flow

C provides statements that control the flow of program execution:

• if-else statement: Execute a block of code based on a condition.
• Loop: Repeat a block of code, such as the for loop and the while loop.

Functions

Functions are reusable blocks of code. You can define a function that does not return a value by using the void keyword, for example:

void print_message() {
    printf("这是来自函数的消息！\n");
}

Practical case: Calculate the area of ​​a circle

#include 
#include 

int main() {
    float radius;

    printf("请输入圆的半径：");
    scanf("%f", &radius);

    float area = M_PI * radius * radius;

    printf("圆的面积为：%f\n", area);

    return 0;
}

This program prompts the user to enter the radius of a circle, calculates the area of ​​the circle, and prints the result.