该代码未检查无效的utf8字符串。返回所有输入的有效字符串

Question

我已经编写了用于验证非utf8字符串的代码。但是代码给出的输出表明该字符串是有效的。即使我们输入了无效字符，也会通过编辑器编码将其转换为有效utf8。需要帮助使用无效的utf8字符。需要包含无效utf8字符的字符串的帮助。 我提供了不同的输入，这些输入是无效的utf8字符。但是代码给出的输出是有效的字符串。我正在Linux中构建代码

#include <iostream>
#include <string.h>
using namespace std;
bool bFixString (char  * Utf8) ;

int main()
{
char * sequence = "ðŸŒ";
int len = strlen(sequence) ;
cout << "String length = " << len <<endl;
cout << "Original String:" << sequence << endl;
bool s = bFixString(sequence);
cout << s <<endl;
return 0 ;
}

bool bFixString ( char * Utf8) 
{
   unsigned char * p = ( unsigned char *)Utf8;
   unsigned int cnt,t;
   int i=0;
   bool result = false;
   while (p[i]  != NULL)
   {
       if (p[i] >= 0xC0)
       {
           // Is a multi-byte symbol. Count bytes needed for this symbol
           for (cnt = 2; cnt < 7; cnt++)
               if (!(p[i] & (0x80 >> cnt)))
               {
                   break;
               }
           // now we need this number of corret continue-bytes.
           for (t = 1; t < cnt; t++)
           {
               if (((p[i+t]) & 0xC0u) != 0x80)
               {
                   // bad follow-up sequence
                   p[i] = '?';       // overwrite first byte (!) with a question mark. Follow-up bytes will be overwritten later in the loop.
                   cnt = 1;
                   result = true;
                   break;

               }
           }
           // skip to next.
           i+= cnt;
           continue;
       }
       else if (p[i] >= 0x80)
       {
           // unexpected second byte
           p[i] = '?';
           result = true;
       }
       // Otherwise, its a normal character.
       i++;
   }
   cout<<"changed string :"<<p<<endl;
   return result;
}

预期结果是返回值应为1，无效字符应替换为“？”但返回0。