字符串指针数组训练

1. 题目: 输入一个字符串,同时输入帧头和帧尾(可以是多个字符),将该字符串中合法的帧识别出来.

提示:帧头和帧尾分别是head和tail  字符串”asdheadhauboisoktail”中headhauboisoktail是合法帧

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

int main()
{
	char *str,s1[5],s2[5];
	int i, j, k;
	str = (char *)malloc(sizeof(char) * 32);
	int len1, len2, len3;

	printf("Please input string: \n");
	scanf("%s%s%s",str,s1,s2);

	len1 = strlen(str);
	len2 = strlen(s1);
	len3 = strlen(s2);

	for(i = 0; i < len1 - len2 - len3 + 1; i++)
	{
		if (strncmp(str + i, s1, len2) == 0)
		{
			for(k = i + len2; k < len1 - len3 + 1;k++)
			{
				if (strncmp(str + k, s2, len3) == 0)
				{
					for(j = i; j < k + len3; j++)
					{
						printf("%c",str[j]);
					}
					break;
				}
				else
					continue;
			}
		}
		else 
			continue;
	}
	printf("\n");

	return 0;
}

2. 题目：编写一个C函数,将”I am from shanghai ”倒置为”shanghai from am I”,即将句子中的单词位置倒置,而不改变单词内部结构.

#include <stdio.h>
#include <string.h>

int main()
{
	int i,temp;
	char *ch[] = {"I","am","from","shanghai"};
	
	for(i = 0; i < 2; i++)
	{
		temp = ch[i];
		ch[i] = ch[3 - i];
		ch[3 - i] = temp;
	}

	for(i = 0; i < 4; i++)
	printf("%s ",ch[i]);
    
	printf("\n");

	return 0;
}

3.冒泡排序字符串

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

void sort(char *str[], int n)
{
    char *temp; 
    temp = (char *)malloc(sizeof(char) * 50);
    int i, j;

    for (i = 0; i < n - 1; i++)
    {
        for (j = i + 1; j n; j++)
        {
            if (strcmp(str[i], str[j]) > 0)
            {
                strcpy(temp, str[j]);
                strcpy(str[j], str[i]);
                strcpy(str[i], temp);
            }
        }
    }
    
	for (i = 0; i < n; i++)
    {
        printf("  %s", str[i]);
    }
}

int main()
{
    char *str[50];
    int n, i;

	printf("Please input n:");
    scanf("%d", &n);
    printf("Please input n string:");
    for (i = 0; i < n; i++)
    {
        str[i] = (char *)malloc(sizeof(char) * 20);
        scanf("%s", str[i]);
    }
    
	sort(str, n);
	printf("\n");
    
	return 0;
}