#include "stdio.h" char FirstNotRepeatingChar(char* pString){    unsigned int i;      // invalid input      if(!pString)            return 0;      // get a hash table, and initialize it       const int tableSize = 256;      unsigned int hashTable[tableSize];      for(i = 0; i < tableSize; ++ i)            hashTable[i] = 0;      // get the how many times each char appears in the string      char* pHashKey = pString;      while(*(pHashKey) != ‘\0‘)            hashTable[*(pHashKey++)] ++;      // find the first char which appears only once in a string      pHashKey = pString;      while(*pHashKey != ‘\0‘)      {            if(hashTable[*pHashKey] == 1)                  return *pHashKey;            pHashKey++;      }      // if the string is empty       // or every char in the string appears at least twice      return 0;}   int main() {      printf("%c",FirstNotRepeatingChar("abaccdeff"));     return 0; }