Qt - 將int轉換爲文件大小格式（KB，MB或GB）的最簡單方法？

Question

什麼是文件大小的int轉換爲字符串的文件大小的格式，如最簡單的方法：

2048 to 2 KB 
4086 KB to 4 MB 

，而不是在QT5如何計算呢？

Answer 1

QFileInfo沒有一個具體方法爲，但here你可以找到一個簡單的實現子類QFileInfo和實施這種新方法

QString QFileInfoHumanSize::size_human() 
{ 
    float num = this->size(); 
    QStringList list; 
    list << "KB" << "MB" << "GB" << "TB"; 

    QStringListIterator i(list); 
    QString unit("bytes"); 

    while(num >= 1024.0 && i.hasNext()) 
    { 
     unit = i.next(); 
     num /= 1024.0; 
    } 
    return QString().setNum(num,'f',2)+" "+unit; 
} 

Answer 2

下面是一個最小的代碼，可以這樣做。

char unit; 
const char *units [] = {" Bytes", " kB", " MB", " GB"}; 
quint64 size = 102400; // or whatever 

for (unit=-1; (++unit<3) && (size>1023); size/=1024); 
qlabel->setText (QString::number (size, 'f', 1) + units[unit]); 

Answer 3

@danielfranca提供的代碼在使用int而不是float時會導致稍微不正確的結果。以下是報告的結果爲整數更精確的版本：

QString MyClass::convertFileSizeToHumanReadable(const qlonglong & bytes) 
{ 
    QString number; 

    if(bytes < 0x400) //If less than 1 KB, report in B 
    { 
     number = QLocale::system().toString(bytes); 
     number.append(" B"); 
     return number; 
    } 
    else 
    { 
     if(bytes >= 0x400 && bytes < 0x100000) //If less than 1 MB, report in KB, unless rounded result is 1024 KB, then report in MB 
     { 
      qlonglong result = (bytes + (0x400/2))/0x400; 

      if(result < 0x400) 
      { 
       number = QLocale::system().toString(result); 
       number.append(" KB"); 
       return number; 
      } 
      else 
      { 
       qlonglong result = (bytes + (0x100000/2))/0x100000; 
       number = QLocale::system().toString(result); 
       number.append(" MB"); 
       return number; 
      } 
     } 
     else 
     { 
      if(bytes >= 0x100000 && bytes < 0x40000000) //If less than 1 GB, report in MB, unless rounded result is 1024 MB, then report in GB 
      { 
       qlonglong result = (bytes + (0x100000/2))/0x100000; 

       if(result < 0x100000) 
       { 
        number = QLocale::system().toString(result); 
        number.append(" MB"); 
        return number; 
       } 
       else 
       { 
        qlonglong result = (bytes + (0x40000000/2))/0x40000000; 
        number = QLocale::system().toString(result); 
        number.append(" GB"); 
        return number; 
       } 
      } 
      else 
      { 
       if(bytes >= 0x40000000 && bytes < 0x10000000000) //If less than 1 TB, report in GB, unless rounded result is 1024 GB, then report in TB 
       { 
        qlonglong result = (bytes + (0x40000000/2))/0x40000000; 

        if(result < 0x40000000) 
        { 
         number = QLocale::system().toString(result); 
         number.append(" GB"); 
         return number; 
        } 
        else 
        { 
         qlonglong result = (bytes + (0x10000000000/2))/0x10000000000; 
         number = QLocale::system().toString(result); 
         number.append(" TB"); 
         return number; 
        } 
       } 
       else 
       { 
        qlonglong result = (bytes + (0x10000000000/2))/0x10000000000; //If more than 1 TB, report in TB 
        number = QLocale::system().toString(result); 
        number.append(" TB"); 
        return number; 
       } 
      } 
     } 
    } 
} 

Answer 4

的Qt 5.10先後引進ready solution：

QLocale locale = this->locale(); 
QString valueText = locale.formattedDataSize(sizeValue);