C语言指针使用例（指针自加自减运算、数组与指针、字符串与指针）

布满荆棘的人生 2023-07-02 10:24 3阅读 0赞

1.在一个已按升序排列的数组中插入一个数，插入后，数组元素仍按升序排列

#include<stdio.h>
    #define	N 10
    void fun(int *a)
    {
    	int number,i;
    	printf("Please enter a integer to insert in the array:");
    	scanf("%d", &number);
    	for (i = N - 2; i >= 0; i--)
    	{
    		if (number <= *(a + i))
    		{
    			*(a + i + 1) = *(a + i);
    		}
    		else
    		{
    			*(a + i + 1) = number;
    			break;
    		}
    	}
    	if (number < *a)
    	{
    		*a = number;
    	}
    	printf("The result array:");
    	for (i = 0; i < N; i++)
    	{
    		printf("%5d", *(a + i));
    	}
    	printf("\n");
    }
    
    void main()
    {
    	int number;
    	int i;
    	int a[N] = { 11,22,33,44,55,66,77,88,99 };
    	printf("The original array:");
    	for (i = 0; i < N-1; i++)
    	{
    		printf("%5d", *(a+i));
    	}
    	printf("\n");
    	fun(a);
    }

![20200129212708741.png][]

2.函数comb(char \*a,char \*b)将字符串a逆序后，再在尾部接上字符串b

#include<stdio.h>
    #include<string.h>
    void comb(char *a, char *b)
    {
    	int i, j;
    	int len = strlen(a);
    	char c;
    	for (i = 0; i < len / 2; i++)
    	{
    		c = *(a + i);
    		*(a + i) = *(a + len - i - 1);
    		*(a + len - i - 1) = c;
    	}
    	*(a + len++) = ' ';
    	j = 0;
    	while (*(a + len + j) = *(b + j++));
    }
    
    void main()
    {
    	char a[100] = "margorP C";
    	char b[] = "Design";
    	comb(a, b);
    	printf("%s\n", a);
    }

![20200129212824571.png][]

3.输入一维数组的10个元素，最大的与a\[9\]交换，最小的与a\[0\]交换，输出数组的10个元素

#include<stdio.h>
    #include<stdlib.h>
    #include<string.h>
    void input(int number[])
    {
    	int i;
    	for (i = 0; i < 10; i++)
    	{
    		scanf("%d", &number[i]);
    	}
    }
    
    void max_min(int array[])
    {
    	int *max, *min;
    	int *p, *arr_end;
    	arr_end = array + 10;
    	max = min = array;
    	for (p = array + 1; p < arr_end; p++)    //for循环结束后p指向array[10]的地址
    	{
    		if(*p>*max)
    		{
    			max = p;
    		}
    		else if(*p<*min)
    		{
    			min = p;
    		}
    	}
    	
    	*p = array[0];    //借助array[10]进行交换
    	array[0] = *min;
    	*min = *p;
    	
    	*p = array[9];
    	array[9] = *max;
    	*max = *p;
    }
    
    void output(int array[]) 
    {
    	int *p;
    	for (p = array; p < array + 10; p++)
    	{
    		printf("%d ",*p);
    	}
    }
    
    void main()
    {
    	int number[11];
    	input(number);
    	printf("\n");
    	max_min(number);
    	output(number);
    }

![20200129215338524.png][]

4.输出两个整数中较大的数，两个整数由键盘输入

#include<stdio.h>
    #include<stdlib.h>
    void main()
    {
    	int *p1, *p2;
    	p1 = (int*)malloc(sizeof(int));
    	p2 = (int*)malloc(sizeof(int));
    	scanf("%d%d", p1, p2);
    	if (*p2 > *p1)
    	{
    		*p1 = *p2;
    	}
    	free(p2);
    	printf("%d\n", *p1);
    	free(p1);
    }

![20200129215603855.png][]

5.删除字符串中的数字字符

#include<stdio.h>
    #include<string.h>
    void fun(char *s)
    {
    	char *p = s;
    	while (*p)
    	{
    		if ((*p >= '0') && (*p <= '9'))
    		{
    			p++;
    		}
    		else
    		{
    			*(s++) = *(p++);
    		}
    	}
    	*s = '\0';
    }
    void main()
    {
    	char item[100];
    	printf("Enter a string:");
    	gets_s(item);
    	fun(item);
    	printf("%s\n", item);
    }

![20200129215917839.png][]

6.将s所指字符串的正序和反序进行连接，形成一个新串放在t所指的数组中

#include<stdio.h>
    #include<string.h>
    void fun(char *s,char *t)
    {
    	int i, d;
    	d = strlen(s);
    	for (int i = 0; i < d; i++)
    	{
    		t[i] = s[i];
    	}
    	for (int i = 0; i < d; i++)
    	{
    		t[i + d] = s[d - 1 - i];
    	}
    	t[2 * d] = '\0';
    }
    void main()
    {
    	char s[100], t[100];
    	printf("Please enter string:");
    	scanf("%s", s);
    	fun(s, t);
    	printf("\nThe result is:%s\n", t);
    }

![20200129220101598.png][]

7.从键盘接收一个字符串，然后按字符顺序从小到大进行排序，并删除重复的字符

#include<stdio.h>
    #include<string.h>
    void main()
    {
    	char str[100], *p, *q, *r, c;
    	printf("输入字符串:");
    	gets_s(str);
    	for (p = str; *p; p++)
    	{
    		for (q = r = p; *q; q++)
    		{
    			if (*r > *q)
    			{
    				r = q;
    			}
    		}
    		if (r != p)
    		{
    			c = *r;
    			*r = *p;
    			*p = c;
    		}
    	}
    	for (p = str; *p;p++)
    	{
    		for (q = p+1 ; *p == *q;)
    		{
    			strcpy(p, q);
    		}
    	}
    	printf("结果字符串:%s\n", str);
    }

![20200129225659735.png][]

8.统计字符串中单词的个数

#include<stdio.h>
    int wordCount(char *s)
    {
    	int num = 0,i,word=0;
    	while (*s != '\0')
    	{
    		if (*s == ' ')
    		{
    			word = 0;
    		}
    		else if (word == 0)
    		{
    			word = 1;
    			num++;
    		}
    		s++;
    	}
    	return(num);
    }
    void main()
    {
    	char str[101];
    	int wordnum;
    	printf("输入不超过100字符的字符串:");
    	gets_s(str);
    	wordnum = wordCount(str);
    	printf("有%d个单词\n", wordnum);
    }

![20200129230353674.png][]

9.将一个3行5列的二维数组的第二行元素输出

#include<stdio.h>
    void main()
    {
    	int a[3][5],i,j;
    	printf("please input:\n");
    	for (i = 0; i < 3; i++)
    	{
    		for (j = 0; j < 5; j++)
    		{
    			scanf("%d", *(a + i) + j);
    		}
    	}
    	printf("The second line is:");
    	for (j = 0; j < 5; j++)
    	{
    		printf("%5d", *(*(a + 1) + j));
    	}
    	printf("\n");
    }

![20200129232140457.png][]

[20200129212708741.png]: https://img-blog.csdnimg.cn/20200129212708741.png
[20200129212824571.png]: https://img-blog.csdnimg.cn/20200129212824571.png
[20200129215338524.png]: https://img-blog.csdnimg.cn/20200129215338524.png
[20200129215603855.png]: https://img-blog.csdnimg.cn/20200129215603855.png
[20200129215917839.png]: https://img-blog.csdnimg.cn/20200129215917839.png
[20200129220101598.png]: https://img-blog.csdnimg.cn/20200129220101598.png
[20200129225659735.png]: https://img-blog.csdnimg.cn/20200129225659735.png
[20200129230353674.png]: https://img-blog.csdnimg.cn/20200129230353674.png
[20200129232140457.png]: https://img-blog.csdnimg.cn/20200129232140457.png