How to use malloc in c language

Usage of malloc() in C language

malloc() is a function used for dynamic memory allocation in the C language standard library. It allocates a memory block of a specific size and returns a pointer to the block.

Syntax:

void *malloc(size_t size);

Parameters:

• size: The memory to be allocated Size (in bytes).

Return value:

If the allocation is successful, malloc() will return a pointer to the starting address of the allocated memory block. If the allocation fails (for example, there is not enough memory available), it returns NULL.

Usage:

1. Allocate memory:

   • Use malloc() to allocate specific size memory block.
   • Store the returned pointer in a variable to access the allocated memory.

2. Use allocated memory:

   • Use pointers to access and operate on allocated memory.
   • Data can be copied to and retrieved from memory blocks.

3. Release allocated memory:

   • When the allocated memory is no longer needed, use free( ) function releases it.
   • This will free up the memory so that other programs can use it again.

Example:

#include <stdio.h>
#include <stdlib.h>

int main() {
    int *ptr;

    // 分配 10 个 int 大小的内存块
    ptr = (int *)malloc(10 * sizeof(int));

    // 检查分配是否成功
    if (ptr == NULL) {
        perror("malloc failed");
        exit(EXIT_FAILURE);
    }

    // 使用已分配的内存
    ptr[0] = 10;
    printf("ptr[0] = %d\n", ptr[0]);

    // 释放已分配的内存
    free(ptr);

    return 0;
}

Advantages:

• Dynamic memory allocation Allows the program to allocate the required memory size at runtime.
• It enables programmers to allocate memory when needed and free it to avoid memory leaks.

Disadvantages:

• If the allocation fails, malloc() will return NULL, which may cause the program to crash.
• Dynamic memory allocation requires careful management to avoid memory leaks and memory errors.

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