<HEAD> <SCRIPT language="JavaScript"><!-- r = new Array(2) function setStartState(){ state="start" r[0] = "0" r[1] = "0" operator="" ix=0 } function addDigit(n){ if(state=="gettingInteger" || state=="gettingFloat") r[ix]=appendDigit(r[ix],n) else{ r[ix]=""+n state="gettingInteger" } display(r[ix]) } function appendDigit(n1,n2){ if(n1=="0") return ""+n2 var s="" s+=n1 s+=n2 return s } function display(s){ document.calculator.total.value=s } function addDecimalPoint(){ if(state!="gettingFloat"){ decimal=true r[ix]+="." if(state=="haveOperand" || state=="getOperand2") r[ix]="0." state="gettingFloat" display(r[ix]) } } function clearDisplay(){ setStartState() display(r[0]) } function changeSign(){ if(r[ix].charAt(0)=="-") r[ix]=r[ix].substring(1,r[ix].length) else if(parseFloat(r[ix])!=0) r[ix]="-"+r[ix] display(r[ix]) } function calc(){ if(state=="gettingInteger" || state=="gettingFloat" || state=="haveOperand"){ if(ix==1){ r[0]=calculateOperation(operator,r[0],r[1]) ix=0 } }else if(state=="getOperand2"){ r[0]=calculateOperation(operator,r[0],r[0]) ix=0 } state="haveOperand" decimal=false display(r[ix]) } function calculateOperation(op,x,y){ var result="" if(op=="+"){ result=""+(parseFloat(x)+parseFloat(y)) }else if(op=="-"){ result=""+(parseFloat(x)-parseFloat(y)) }else if(op=="*"){ result=""+(parseFloat(x)*parseFloat(y)) }else if(op=="/"){ if(parseFloat(y)==0){ alert("Division by 0 not allowed.") result=0 }else result=""+(parseFloat(x)/parseFloat(y)) } return result } function performOp(op){ if(state=="start"){ ++ix operator=op }else if(state=="gettingInteger" || state=="gettingFloat" || state=="haveOperand"){ if(ix==0){ ++ix operator=op }else{ r[0]=calculateOperation(operator,r[0],r[1]) display(r[0]) operator=op } } state="getOperand2" decimal=false } // --></SCRIPT> </HEAD> <BODY> <SCRIPT LANGUAGE="JavaScript"><!-- setStartState() // --></SCRIPT> <div align=center> <FORM NAME="calculator"> <TABLE BORDER="BORDER" ALIGN="CENTER"> <TR> <TD COLSPAN="3"><INPUT TYPE="TEXT" NAME="total" VALUE="0" SIZE="15"></TD></TR> <TR> <TD><INPUT TYPE="BUTTON" NAME="n0" STYLE="width:40px" WIDTH="40" VALUE=" 0 " ONCLICK="addDigit(0)"></TD> <TD><INPUT TYPE="BUTTON" NAME="n1" STYLE="width:40px" WIDTH="40" VALUE=" 1 " ONCLICK="addDigit(1)"></TD> <TD><INPUT TYPE="BUTTON" NAME="n2" STYLE="width:40px" WIDTH="40" VALUE=" 2 " ONCLICK="addDigit(2)"></TD> </TR> <TR> <TD><INPUT TYPE="BUTTON" NAME="n3" STYLE="width:40px" WIDTH="40" VALUE=" 3 " ONCLICK="addDigit(3)"></TD> <TD><INPUT TYPE="BUTTON" NAME="n4" STYLE="width:40px" WIDTH="40" VALUE=" 4 " ONCLICK="addDigit(4)"></TD> <TD><INPUT TYPE="BUTTON" NAME="n5" STYLE="width:40px" WIDTH="40" VALUE=" 5 " ONCLICK="addDigit(5)"></TD> </TR> <TR> <TD><INPUT TYPE="BUTTON" NAME="n6" STYLE="width:40px" WIDTH="40" VALUE=" 6 " ONCLICK="addDigit(6)"></TD> <TD><INPUT TYPE="BUTTON" NAME="n7" STYLE="width:40px" WIDTH="40" VALUE=" 7 " ONCLICK="addDigit(7)"></TD> <TD><INPUT TYPE="BUTTON" NAME="n8" STYLE="width:40px" WIDTH="40" VALUE=" 8 " ONCLICK="addDigit(8)"></TD> </TR> <TR> <TD><INPUT TYPE="BUTTON" NAME="n9" STYLE="width:40px" WIDTH="40" VALUE=" 9 " ONCLICK="addDigit(9)"></TD> <TD><INPUT TYPE="BUTTON" NAME="decimal" STYLE="width:40px" WIDTH="40" VALUE=" . " ONCLICK="addDecimalPoint()"></TD> <TD><INPUT TYPE="BUTTON" NAME="plus" STYLE="width:40px" WIDTH="40" VALUE=" + " ONCLICK="performOp('+')"></TD> </TR> <TR> <TD><INPUT TYPE="BUTTON" NAME="minus" STYLE="width:40px" WIDTH="40" VALUE=" - " ONCLICK="performOp('-')"></TD> <TD><INPUT TYPE="BUTTON" NAME="multiply" STYLE="width:40px" WIDTH="40" VALUE=" x " ONCLICK="performOp('*')"></TD> <TD><INPUT TYPE="BUTTON" NAME="divide" STYLE="width:40px" WIDTH="40" VALUE=" / " ONCLICK="performOp('/')"></TD> </TR> <TR> <TD><INPUT TYPE="BUTTON" NAME="equals" STYLE="width:40px" WIDTH="40" VALUE=" = " ONCLICK="calc()"></TD> <TD COLSPAN="1" ROWSPAN="1"><INPUT TYPE="BUTTON" NAME="sign" STYLE="width:40px" WIDTH="40" VALUE=" +/- " ONCLICK="changeSign()"></TD> <TD><INPUT TYPE="BUTTON" NAME="clearField" STYLE="width:40px" WIDTH="40" VALUE=" C " ONCLICK="clearDisplay()"></TD> </TR> </TABLE> </FORM> </BODY>