Google Apps Script入門
第8回.最終行を取得して繰り返す

function mySample4() {
  var sheet = SpreadsheetApp.getActiveSheet()
  var tannka,suuryou
  for (var i=2; i<=11; i++) {
    tannka = sheet.getRange(i, 2).getValue()
    suuryou = sheet.getRange(i, 3).getValue()
    sheet.getRange(i, 4).setValue(tannka * suuryou) 
  }
}

function mySample5() {
  var sheet = SpreadsheetApp.getActiveSheet()
  var tannka,suuryou,lastRow
  lastRow = sheet.getLastRow()
  for (var i=2; i<=lastRow; i++) {
    tannka = sheet.getRange(i, 2).getValue()
    suuryou = sheet.getRange(i, 3).getValue()
    sheet.getRange(i, 4).setValue(tannka * suuryou) 
  }
}

function mySample6() {
  var sheet = SpreadsheetApp.getActiveSheet()
  var tannka,suuryou,lastRow
  lastRow = sheet.getLastRow()
  for (var i=2; i<=lastRow; i++) {
    if (sheet.getRange(i, 2).getValue() == "") break
    tannka = sheet.getRange(i, 2).getValue()
    suuryou = sheet.getRange(i, 3).getValue()
    sheet.getRange(i, 4).setValue(tannka * suuryou) 
  }
}

function mySample7() {
  var sheet = SpreadsheetApp.getActiveSheet()
  var tannka,suuryou,lastRow
  lastRow = getLastRow(sheet,1)
  for (var i=2; i<=lastRow; i++) {
    tannka = sheet.getRange(i, 2).getValue()
    suuryou = sheet.getRange(i, 3).getValue()
    sheet.getRange(i, 4).setValue(tannka * suuryou) 
  }
}
function getLastRow(sheet,col){
  var lastRow = 1
  for (var i=sheet.getLastRow(); i>1; i--) {
    if(sheet.getRange(i, col).getValue() != "") {
      lastRow = i
　　　break;
　　}
　}
  return lastRow
}