C语言指针引用数组案例讲解

#include<stdio.h>

//值传递
void swap1(int x, int y) {
	int z;
	z = x;
	x = y;
	y = z;
}

//地址传递 
void swap2(int *p1, int *p2) {
	int t = *p1;
	*p1 = *p2;
	*p2 = t;
}

 
//void swap3(int *p1, int *p2) {
//	int *t;
//	*t = *p1;
//	p1 = *p2;	//报错 
//	p2 = *t;
//}

 
void swap4(int *p1, int *p2) {
	int *t = NULL;
	t = p1;
	p1 = p2;
	p2 = t;
}

int main() {
	int a, b;
	scanf("%d %d", &a, &b);
	
	swap1(a, b);
	printf("%d %d\n", a, b);
	
	int *p1 = &a, *p2 = &b;
	
	swap2(p1, p2);
	printf("%d %d\n", a, b);
	
	swap4(p1, p2);
	printf("%d %d\n", *p1, *p2);	//注：在swap2()函数中，a b的值发生了交换 
	
	return 0;	
}

 

#include<stdio.h>
int main() {
	int a[5];
	
	//下标法
	for(int i = 0; i < 5; i++) 
		scanf("%d", &a[i]);				//等价于scanf("%d", a + i);
	int *p, *p1;
	
	p = a;								//等价于p = &a[0] 
	p1 = &a[0];
	
	for(int i = 0; i < 5; i++)
		printf("%d ", a[i]);
	printf("\n");

	//指针法
	
	
	*/
			
	for(int i = 0; i < 5; i++) 
		printf("%d ", *(p + i));		
	printf("\n");
	
	//a为指针常量不能改变，变的是 a + i本身 
	for(int i = 0; i < 5; i++) 
		printf("%d ", *(a + i));		
	printf("\n");
	
	//指针p在不断移动，因此在学习的过程中要时刻注意指针的位置！！！ 
	for(int p = a; p < (a + 5); p++)
		printf("%d ", *p); 
	return 0; 
}


#include<stdio.h>

void swap(int a[], int n) {
	int h = 0, t = n - 1, m = (n - 1) / 2;
	for(h; h <= m; h++) {
		int tmp = a[h];
		a[h] = a[t];		//根据须知3： a[h]等价于*(a+h) 
		a[t] = tmp;
		t--;
	}
}

void swap1(int *x, int n) {
	int *p, *i, *j;
	i = x;
	j = x + n - 1;
	p = x + (n - 1) / 2;

	for( ; i <= p; i++, j--) {
		int tmp = *i;
		*i = *j;
		*j = tmp;
	}
}

int main() {
	int a[10] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
	for(int i = 0; i < 10; i++) 
		printf("%d ", a[i]);
	printf("\n"); 
	swap(a, 10);
	for(int i = 0; i < 10; i++) 
		printf("%d ", a[i]);
	printf("\n");
		
	swap1(a, 10);
	for(int i = 0; i < 10; i++) 
		printf("%d ", a[i]);
	printf("\n");
	return 0;	
} 
 

#include<stdio.h>
int main() {
	int a[3][4] = {1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23};
	 
	printf("%d %d\n", a, *a);			//a:表示0行首地址	  *a:表示0行0列元素的地址	二者的值一样，但是指针类型不同					 
	printf("%d %d\n", a[0], *(a + 0));			 
	printf("%d %d\n", &a[0], &a[0][0]);	 
	printf("%d %d\n", a[1], a + 1);
	printf("%d %d\n", &a[1][0], *(a + 1) + 0);
	printf("%d %d\n", a[2], *(a + 2));
	printf("%d %d\n", &a[2], a + 2);
	printf("%d %d\n", a[1][0], *(*(a + 1) + 0));
	printf("%d %d\n", *a[2], *(*(a + 2) + 0));
	return 0;
}

 

#include<stdio.h>
int main() {
	int a[3][4] = {1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23};
	
	 
	int *p;
	for(p = a[0]; p < a[0] + 12; p++) {
		printf("%2d ", *p);
		
	}
	printf("\n\n");
	
	 
	int (*q)[4] = a;				//指针变量p指向4个整形元素的一维数组 
	for(int i = 0; i < 3; i++) {
		for(int j = 0; j < 4; j++) {
			printf("%2d ", *(*(q + i) + j));
		}
	}
	 
	return 0;
} 

#include<stdio.h>
//指向变量的指针变量
void avg(float *p, int n) {
	float sum = 0, ans = 0;
	float *p1 = p + 11;
	for(p; p <= p1; p++)
		sum = sum + *p;
	ans = sum / n;
	printf("%.2f\n", ans);
}
//指向一维数组的指针变量
void search(float (*p)[4], int n) {
	for(int i = 0; i < 4; i++) {
		printf("%.2f ", *(*(p + n) + i));
	}
}
int main() {
	float score[3][4] = {78, 90, 89, 34, 91, 61, 71, 84, 67, 76, 100, 53};
	avg(*score,12);	 
	search(score, 2);		 
	return 0;
}