C Programming Fundamentals: Laying the Foundation for Systems Development

C language is a procedural programming language known for its efficiency, portability and control of hardware, and is the foundation of modern computer science. Its basic syntax includes header file inclusion, main function, data types (integers, floating point numbers, characters, strings, arrays, pointers) and control structures (if-else, loops, switch statements). Pointers are a unique feature of the C language that allow direct access to memory addresses.

C Programming Fundamentals: The cornerstone of system development

C language is a powerful procedural programming language known for its high efficiency , portability and direct control over hardware. It formed the foundation of modern computer science and is still widely used today to develop operating systems, embedded systems, and a variety of other mission-critical applications.

Basic syntax

C language syntax is very concise and is a solid foundation for building complex programs. It follows the following basic syntax structure:

#include <stdio.h> //包含头文件

int main() { //主函数
    printf("Hello, World!\n"); //输出文本
    return 0; //返回状态代码
}

Data type

The C language provides various data types to represent different types of data:

• Integer: char, int, long
• Floating point: float, double
• Character: char
• String: char[]
• Array: type name[]
• Pointer: type name*

Control structure

C language uses various control structures to control Program flow:

• if-else statement: execute code based on conditions
• Loop: while, do-while, for loop
• Switch statement: based on expression Values ​​execute different blocks of code

Pointers

Pointers are a unique and powerful feature in C language that allow direct access to memory addresses. They are used for dynamic memory allocation and manipulation of low-level data structures:

int* ptr; //声明一个指向 int 的指针
int var = 10;
ptr = &var; //将指针指向 var 的地址
*ptr = 20; //通过指针修改 var 的值

Practical Case: Calculating Factorial

Let us write a practical case using C language to calculate a Factorial of numbers:

#include <stdio.h>

int factorial(int n) { //计算阶乘的函数
    if (n == 0) //基例
        return 1;
    else
        return n * factorial(n - 1); //递归调用
}

int main() {
    int num, result;
    printf("输入一个数字：");
    scanf("%d", &num);
    result = factorial(num);
    printf("%d 的阶乘为：%d\n", num, result);
    return 0;
}

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