苏嵌第七天

1.请编写一个C函数,该函数将一个字符串逆序

#include <stdio.h>
#include <string.h>
char *reserve(char *s)
{
    int i;    
    int n = strlen(s)/2；
    char tmp;
    for(i = 0; i <= n; i++)  
    {
        tmp = s[i];
        s[i] = s[strlen(s)-i-1];
        s[strlen(s)-i-1] = tmp;
    }
    return s;   
}
int main()
{
    char str[20];
    printf("Please input a string:\n");
    scanf("%s", str);
    printf("\nThe reserved string is:\n%s\n", reserve(str));
    return 0;
}

2.请编写一个C函数,该函数可以实现将一个整数转为任意进制的字符串输出

#include <stdio.h>
void Transfer(int num, int radix, int *Arr)
{
int i = 0;
int temp = 0;
if (radix == 2) 
{
while (num)
{
Arr[i++] = num % 2;
num /= 2;
}
printf ("num = ");
while (i)
{
printf ("%d", Arr[--i]);
}
printf ("B\n");
}
else if (radix == 8) 
{
while (num)
{
Arr[i++] = num % 8;
num /= 8;
}
printf ("num = ");
while (i)
{
printf ("%d",Arr[--i]);
}
printf ("O\n");
}
else if (radix == 16) 
{
while (num)
{
temp = num % 16;
switch(temp)
{
case 1:Arr[i++] = '1';break;
case 2:Arr[i++] = '2';break;
case 3:Arr[i++] = '3';break;
case 4:Arr[i++] = '4';break;
case 5:Arr[i++] = '5';break;
case 6:Arr[i++] = '6';break;
case 7:Arr[i++] = '7';break;
case 8:Arr[i++] = '8';break;
case 9:Arr[i++] = '9';break;
case 10:Arr[i++] = 'A';break;
case 11:Arr[i++] = 'B';break;
case 12:Arr[i++] = 'C';break;
case 13:Arr[i++] = 'D';break;
case 14:Arr[i++] = 'E';break;
case 15:Arr[i++] = 'F';break;
default:printf ("error!\n");
}
num /= 16;
}
while (i)
{
printf ("%c", Arr[--i]);
}
printf ("H\n");
}
}
int main()
{
int num = 0;
int radix = 0;
int Arr[100] = {0};
printf ("Please input the number : ");
scanf ("%d", &num);
printf ("Please input the radix : ");
scanf ("%d", &radix);
Transfer(num, radix, Arr);
return 0;
}

3.输入一个字符串,计算字符串中子串出现的次字数

#include <stdio.h>
#include <string.h>
int main()
{
    char a[100];
    printf("请输入字符串\n");
    scanf("%s",a);
    char * c = a;
    char b[10];
    printf("请输入子串\n");
    scanf("%s",b);
    char * d = b;
    int n;
    int num = 0;
    n = strlen(d);
    while(strlen(c) > 0)
    {
        if(strncmp(c,d,n) == 0)
        {
            num++;
            c += n;
        }
        else
        {
            c++;
        }
    }
    printf("%d\n",num);
    return 0;
}

4.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>
#include <stdlib.h>
int main()
{
    char *str[] = { "I", "am","from","shanghai" ,NULL};
    int i = 0;
    int j = 0;
    int len  = 0;
    char *temp;
    while (str[i] != NULL)
    {
        i++;
        len++;
    }
    for(i = 0, j = len - 1; j  > i; i++,j--)
    {
        temp =*(str+i);
        *(str+i) = *(str+j);
        *(str+j) = temp;
    }
    for(i = 0; i < len; i++)
    {
        printf("%s ", *(str+i));
    }
    printf("\n");
    return 0;
}

5.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

#include <stdio.h>
int find(char *s,char *a,char *b);
int main()
{
    char s[100],a[100],b[100];       
 printf("Enter the long string : \n");        
 scanf("%s",s);
 printf("Enter the head string : \n");
 scanf("%s",a);
 printf("Enter the tail string : \n");
 scanf("%s",b);
 find(s,a,b);        
    return 0;
}
int find(char *s,char *a,char *b)
{
 int head,tail;        
 int i = 0,j = 0,k = 0,flag = 0;        
 while(s[i] != '\0') 
 {
  if((s[i] == a[j]) && !flag)        
  {
   head = i;        
      while((s[i] == a[j]) && s[i] != '\0')       
      {
       i++;
       j++;
    flag = 1;       
      }
  }
  if((a[j] == '\0') && flag)        
  {
      while((s[i] == b[k]) && s[i] != '\0')       
      {
       i++;
       k++;
    flag = 0;
      }
     }
  if((b[k] == '\0') && !flag)       
  {
   tail = i;
   for(i = head;i < tail;i++)       
   {
    printf("%c",s[i]);
   }
   printf("\n");
   break;
  }
  i++;
 }
 return 0;
}