使用C语言提取子字符串及判断对称子字符串最大长度

#include <stdio.h>

/*处理中文字符*/
/*遍历字符串，非ASCII字符读取2个字节，ASCII读取一个字节，获取字符串长度*/
int StrLenU(const char* string)
{
   int len = 0 ;
   const char* p = string;
   while(*p++ != '\0')
   {
     if(*p > 0x80 || *p < 0)
     {
      p++;
     }
     len++;
   }
   return len;
}
/*遍历字符串，非ASCII字符读取2个字节，ASCII读取一个字节，返回指定位置的字符串指针，默认从1开始*/
char* StrSetPosU(const char* string,int pos)
{
   char* result;
   result = string;
   while (result != NULL && *result != '\0' && pos > 1)
   {
     if(*result > 0x80 || *result < 0)
     {
       result++;
     }
     result++;
     pos--;
   }
   if(pos!=0)
     return result;
   return '\0';
}
/*获取指定内存中的字符串个数，中文字符作为一个字符*/
int StrLenMemU(const char* string,int size)
{  
   int len = 0 ;
   const char* p = string;
   while(*p++ != '\0' && size > 0)
   {
     if(*p > 0x80 || *p < 0)
     {
      p++;
      size--; 
     }
     size-- ;
     len++;
   }
   return len;
}
/*可取中文字符串，当number为-1等负数时，取从start开始的剩余所有字符，默认从1开始*/
char* StringSubU(const char* string,int start,int number)
{
   int len = StrLenU(string) ;
   if(start>len)
   {
     printf("Start %d is too big than string length %d!\n",start,len);
     return NULL;
   }
   int bufsize = 0;
   int num = number;
   const char* p = string;
   const char* start_char =string;
   /*重置指针，获取指定开始位置*/
   p = StrSetPosU(string,start);
   start_char = p;
   /*当取值为负值时，则取全部值*/
   if(number < 0)
   {
     while(*p != '\0')
     {
      p++;
      bufsize++;
     }
   }
   else
   {
     while(1)
     {
      /*当指针移到末尾，而且还没有获取指定数的字符时，说明此时指定字符数过多，将会取剩下的所有值*/
      if(*p == '\0' && num > 0)
      {
        printf("Number : %d is to big!\n",number);
        break;
      }
      /*当num为0时，说明读取字符已经满足要求*/
      else if(num ==0 )
        break;
      /*当字符为ASCII时，*/
      if(*p > 0x80 || *p < 0)
      {
        bufsize++;
        p++;
      }
      bufsize++;
      p++;
      num--;
     }
   }
   num = bufsize;
   /*开始分配内存*/
   char* result ;
   result = (char*)malloc(sizeof(char)*(bufsize+1));
   memset(result,0,sizeof(char)*(bufsize+1));
   /*开始复制字符串*/
   int i = 0;
   int j = 0;
   while(num != 0)
   {
     result[i++] = start_char[j++];
     num--;
   }
   /*尾部置零*/
   result[bufsize] = '\0';
   return result;
}

int main()
{
   /*进行测试*/
   char* t = "a哈哈aab和c哈";
   printf("length: %d\n",StrLenU("哈哈a哈a哈"));
   printf("指向前%s\n指向后:%s\n",t,StrSetPosU(t,3));
   printf("全字符时字符个数:%d\n",StrLenMemU(t,6));
   printf("半个字符时字符个数:%d\n",StrLenMemU(t,4)); 
   printf("1.正常取值:%s\n",StringSubU("a哈aa哈a",1,2));
   printf("2.负值取值:%s\n",StringSubU("a哈aa哈a",-1,2));
   printf("3.起始值过大:%s\n",StringSubU("a哈aa哈a",7,2));
   printf("4.取值过大:%s\n",StringSubU("a哈aa哈a",5,3));
   printf("5.负值取全部:%s\n",StringSubU("a哈aa哈a",4,-1));

   return 0;
}

  #include <stdio.h> 
  #include <stdlib.h> 
  #include <string.h> 
    
  void isSymmetrical(char *str) 
  { 
    char *begin, *end; 
    int flag, len = strlen(str); 
    
    for (begin = str, end = str + len - 1, flag = 1; begin <= end; begin ++, end --) { 
      if (*begin != *end) { 
        flag = 0; 
        break; 
      } 
    } 
    
    if (flag) 
      printf("Yes!\n"); 
    else 
      printf("No!\n"); 
  } 
    
    
  int main(void) 
  { 
    char str[1001]; 
    
    while (gets(str)) { 
      isSymmetrical(str); 
    } 
    
    return 0; 
  } 
    
  

  #include <stdio.h> 
  #include <string.h> 
  #include <stdlib.h> 
    
  /** 
   * 最长回文字串的长度 
   */ 
  void maxSymmetricalSubstring(char *str) 
  { 
    int maxlength, len; 
    char *pre, *next, *current; 
      
    current = str + 1; 
    maxlength = 0; 
    
    while (*current != '\0') { 
      pre = current - 1; 
      next = current + 1; 
    
      while (pre >= str && *next != '\0' && *pre == *next) { 
        pre --; 
        next ++;   
      } 
    
      len = (next - 1) - (pre + 1) + 1; 
        
      if (len > maxlength) { 
        maxlength = len; 
      } 
    
      pre = current - 1; 
      next = current; 
    
      while (pre >= str && *next != '\0' && *pre == *next) { 
        pre --; 
        next ++; 
      } 
      len = (next - 1) - (pre + 1) + 1; 
    
      if (len > maxlength) { 
        maxlength = len; 
      } 
    
      current ++; 
    } 
      
    printf("%d\n", maxlength); 
  }   
    
  int main(void) 
  { 
    char str[101]; 
    
    while (gets(str)) { 
      maxSymmetricalSubstring(str); 
    } 
    
    return 0; 
  }