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struct in c

admin 11月 13, 2020 0

C is a proceduring language.If you want to make a very efficient process,C is a good choice.But I do not introduce everything about C.I just show the detail of C.

Now,i will show the use of struct in C.

Just detail,no grammar.

Struct has two definition.

define

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struct ListNode{
	int val;
	struct ListNode* next;
};

If you use this struct and you want to create a variable.You should do following:

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struct ListNode* n = (struct ListNode*)malloc(sizeof(struct ListNode));

How to assignment.

We also make some mistakes for assignment.Here i will show a wrong example first.

wrong example

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#include <stdlib.h>

struct listNode{
	int value;
	struct listNode* next; 
};

void init(struct listNode* a,int beign,int end){
	a        = (struct listNode*)malloc(sizeof(struct listNode));
	a->value = 1;
	a->next  = NULL;
	for(beign;beign < end;beign++){
		a->next  = (struct listNode*)malloc(sizeof(struct listNode));
		a        = a->next;
		a->value = beign;
		a->next = NULL;
	}
}

int main(){
	struct listNode* a;      //when you create a struct variable.You should give space first.
	struct listNode* b = a;
	init(b,3,10);
	return 0;
}

right example

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#include <stdlib.h>

struct listNode{
	int value;
	struct listNode* next; 
};

void init(struct listNode* a,int beign,int end){
	for(beign;beign < end;beign++){
		a->next  = (struct listNode*)malloc(sizeof(struct listNode));
		a        = a->next;
		a->value = beign;
		a->next = NULL;
	}
}

int main(){
	struct listNode* a = (struct listNode*)malloc(sizeof(struct listNode));
	a->value = 1;
	a->next  = NULL;
	struct listNode* b = a;
	init(b,3,10);
	return 0;
}

operation

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typedef struct ListNode{
	int val;
	struct ListNode* next;
};

If you use this struct and you want to create a variable.You should do following:

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ListNode* n = (ListNode*)malloc(sizeof(ListNode));

How to create list:

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#include <stdlib.h>
typedef struct ListNode{
	int val;
	struct ListNode* next;
};

int main(){
	ListNode* p   = (struct ListNode*)malloc(sizeof(struct ListNode));
	ListNode* l   = p;
	p->val        = 1; 
	p->next       = NULL;
	int i         = 2;
	for(i ;i < 10 ;i++){
		ListNode* n = (ListNode*)malloc(sizeof(ListNode));
		n->val             = i;
		n->next            = NULL;
		p->next            = n;
		p                  = p->next;
	}
	while(l != NULL){
		printf("%d",l->val);
		l  = l->next;
	}
	return 0;
}		//this code maybe not perfect.

Head insertion method:

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#include <stdlib.h>
typedef struct ListNode{
	int val;
	struct ListNode* next;
};

int main(){
	ListNode* p        = (struct ListNode*)malloc(sizeof(struct ListNode));
	ListNode* l;
	p->val             = 1; 
	p->next            = NULL;
	int i = 2;
	for(i ;i < 10 ;i++){
		ListNode* n = (ListNode*)malloc(sizeof(ListNode));
		n->val             = i;
		n->next            = p;
		p                  = n;
		l                  = p;
	}
	while(l != NULL){
		printf("%d",l->val);
		l  = l->next;
	}
	return 0;
}

End insertion method:

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#include <stdlib.h>
typedef struct ListNode{
	int val;
	struct ListNode* next;
};

int main(){
	ListNode* p = (struct ListNode*)malloc(sizeof(struct ListNode));
	ListNode* l = p;
	p->val             = 1; 
	p->next            = NULL;
	int i = 2;
	for(i ;i < 10 ;i++){
		ListNode* n = (ListNode*)malloc(sizeof(ListNode));
		n->val             = i;
		n->next            = NULL;
		p->next            = n;
		p                  = p->next;
	}
	while(l != NULL){
		printf("%d",l->val);
		l  = l->next;
	}
	return 0;
}

Then,I will update.

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