Master the application scenarios and differences of * and & in C language

Pointers (*) store variable addresses and are used to access and modify variable values. The address operator (&) gets the address of a variable, which can be assigned to a pointer or passed to a function. The difference is: pointers can be dereferenced, while address operators themselves cannot access variable values.

Application scenarios and differences between pointers (*) and address operators (&) in C language

Pointers (*)

• Declaration: Use the * symbol, followed by the variable name
• Function: Store the address of the variable

• Purpose:

  • Access and modify the value of the variable (by dereferencing)
  • Pass the variable The address (as a parameter of the function)
  • Implementing dynamic memory allocation

Address operator (&)

• Declaration: Use the & symbol, preceded by the variable name
• Function: Get the address of the variable

• Purpose:

  • Assign the address of the variable to the pointer
  • Pass the address of the variable (as a function parameter)

Difference

• The pointer points to the address of the variable, while the address operator gets the address of the variable.
• Pointers can be dereferenced to access and modify the value of a variable, but the address operator itself cannot access the value of a variable.

Practical case

The following code example demonstrates the use of pointer and address operators in C language:

#include <stdio.h>

int main() {
    int x = 10;

    // 获取 x 的地址并将其赋值给指针 p
    int *p = &x;

    // 使用解引用运算符 * 访问和修改 x 的值
    *p += 5;

    // 打印修改后的 x 值
    printf("x: %d\n", x); // 输出：15

    // 传递 p 指针作为函数的参数
    myFunction(p);

    return 0;
}

void myFunction(int *ptr) {
    // 修改指向值的变量
    *ptr = 20;
}

In this example Medium:

• #*p Dereference pointer p and access the pointed variable x.
• Function myFunction receives a pointer to x p and modifies the value of x through *ptr.

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