How to master the structure of C language
This article mainly introduces the C language structure how to master the relevant knowledge, the content is detailed and easy to understand, the operation is simple and fast, has a certain reference value, I believe everyone read this C language structure how to master the article will have some gains, let's take a look at it.
Examples:
#include //On 32-bit systems, structs are aligned with four bytes by default when alignment is not specified typedef struct __ST{ int id ; //4 char *name ; //4 float math ; //4}ST;int main(){ ST st ; //Gets the first address of the first element of the struct int *ptr_0 = (int *)(&st); printf ("st: %p ptr: %p \n",&st,ptr_0); //assign *ptr_0 = 100 to the first element of the struct; printf ("*ptr_0 = %d\n",*ptr_0); //Get the first address of the second element of the struct, because the second element is a first-level pointer, you need a second-level pointer to connect char **ptr_1 = (char **)((int)&st+4) ; printf ("ptr_1:%p\n", ptr_1); //assign *ptr_1 = "hello world" to the second element of the struct; printf ("ptr_1:%s\n",*ptr_1); //Get the first address of the third element of the structure, calculate the address of the third element according to the alignment offset float *ptr_2 = (float *)((int)&st+8) ; printf ("ptr_2:%p \n", ptr_2); //assigns a value to the third element of the struct *ptr_2 = 96.78 ; printf("ptr_2:%.2f \n",*ptr_2); //prints the values of all members of the struct printf(" st.id = %d st.name = %s st.math = %.2f\n",st.id,st.name,st.math); return 0;}
Isn't the offset calculated according to the alignment principle here actually the principle of offsetof macro?
#define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER) About "How to master C language structure" The content of this article is introduced here, thank you for reading! I believe everyone has a certain understanding of "how to master C language structure" knowledge. If you still want to learn more knowledge, please pay attention to industry information channel.
