c++ - 函数 alnum 未显示正确的金额

Question

我想显示文本文件中字母数字字符的数量，但每次运行代码时，无论我使用哪个文本文件，它都只显示 11 个字符。

// Loop to read from input file
cout << "Reading lines from file '" << INPUT_FILE_NAME
  << "' ..." << endl << endl;
lineCount = 0;
while (inFile.good())
{
  getline(inFile, line);
  
  lineCount = lineCount + 1;
}
 

// Close input file
inFile.close();
cout << endl << lineCount << " line(s) read from file '" 
  << INPUT_FILE_NAME << "'." << endl << endl;


 //count number of alphanumeric char
   
 alnum =0;
 while (isalnum(INPUT_FILE_NAME[alnum])) alnum++;
 printf ("Alphanumeric chars: %d \n",alnum);



 // Show application close
 cout << "End of Text Turtles" << endl;

}

标签： c++