编写搞质量的程序一些技巧总结-优快云博客

本文详细介绍了如何通过使用查表法替代switch/case和if/else语句，以及如何按照定义顺序处理变量来优化代码。同时，强调了代码对齐的重要性，以提升代码可读性和美观性。通过实例展示了优化后的代码更加清晰易懂。

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(1) 用查表法替代又臭又长的switch/case, if/else，且看例子：

不推荐switch/case例子:

int QCleanlooksStyle::pixelMetric(...)
{
  int ret = -1;
  switch (metric) {
    ...
    case PM_SpinBoxFrameWidth:
      ret = 3;
      break;
    case PM_MenuBarItemSpacing:
      ret = 6;
    case PM_MenuBarHMargin:
      ret = 0;
      break;
    ...
}
不推荐if/else例子:

QStringList ProFileEvaluator::Private::values(...)
{
  ...
  else if (ver == QSysInfo::WV_NT)
    ret = QLatin1String("WinNT");
  else if (ver == QSysInfo::WV_2000)
    ret = QLatin1String("Win2000");
  else if (ver == QSysInfo::WV_2000)  <<<=== 2003
    ret = QLatin1String("Win2003");
  else if (ver == QSysInfo::WV_XP)
    ret = QLatin1String("WinXP");
  ...
}

推荐查表法例子：

struct {
  QSysInfo::WinVersion; m_ver;
  const char *m_str;
} Table_WinVersionToString[] = {
  { WV_Me,   "WinMe" },
  { WV_95,   "Win95" },
  { WV_98,   "Win98" },
  { WV_NT,   "WinNT" },
  { WV_2000, "Win2000" },
  { WV_2003, "Win2003" },
  { WV_XP,   "WinXP" },
  { WV_VISTA,"WinVista" }
};

ret = QLatin1String("Unknown");
for (size_t i = 0; i != count_of(Table_WinVersionToString); ++i)
  if (Table_WinVersionToString[i].m_ver == ver)
    ret = QLatin1String(Table_WinVersionToString[i].m_str);

（2）Process variables in the same order as they are defined

按照遍历定义的顺序处理变量

(3)避免 memset,memcpy,ZeroMemory 类似这样的底层函数。

太多了这种代码，容易把内存写坏，定位错误相当困难.

(4) 对齐字符串

代码对齐前，可读性为0:

static BOOL ske_DrawTextEffect(...)
{
  ...
  minX=max(0,minX+mcLeftStart-2);
  minY=max(0,minY+mcTopStart-2);
  maxX=min((int)width,maxX+mcRightEnd-1);
  maxY=min((int)height,maxX+mcBottomEnd-1);
  ...
}

代码对齐后，赏心悦目，好像艺术品:

minX = max(0,              minX + mcLeftStart - 2);
minY = max(0,              minY + mcTopStart  - 2);
maxX = min((int)width,  maxX + mcRightEnd  - 1);
maxY = min((int)height, maxX + mcBottomEnd - 1);