Calculating 2 ^ 10

   // CALCULATE 2 ^ 10
   var base = 2;
   var power = 0;
   var answer = 1; 

   while ( power < 10 )
   {
      answer = base * 2;
      power = power +  1;  
   }

   alert(answer);

Why doesn't this produce 1024? 开发者_StackOverflowIt prints 4.

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It is because base * 2 will always be 4.

I believe this line:

answer = base * 2;

Should be

answer = answer * base;

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This doesn't really answer your question (as to why the wrong value is generated) but you can use Math.pow to calculate the result:

alert(Math.pow(2, 10));

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Your logic is flawed:

...
answer = base * 2; 
...

This resolves to answer = 2 * 2, no matter how many times you increment the loop. base does not change.

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Because answer = base * 2; every iteration. Since base never changes, every iteration you are doing answer = 2 * 2;.

See other answers for what you should be doing.

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This is because no matter how many loop cycles you do, you always multiply base (2) by 2 and assign the result to answer variable. So be it one or million base, the answer will always be 4.

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You need to save the result of each oparation, like this:

    var base = 2;
    var power = 1;
    var answer = 1; 

    answer = base;

     while ( power < 10 ) { 
        answer = answer * base;
        power = power + 1;  
     }

     alert(answer);

This helps you?

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If this is for homework... A dynamic programming solution which will help when you get into recursion and other fun stuff:

This solution is log(y) in terms of calculations.

  function powers(x,y) {
        if(y == 0) {
                return 1;
        } else if(y == 1) {
                return x;
        } else if(y == 2) {
                return x*x;
        } else if(y%2==0) {
                var a = powers(x,y/2); 
                return a * a;
        } else {
                var pow = y-1;
                var a = powers(x,pow/2);
                return x * a * a;
        }
}

If not use Math.pow()

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Why don't you use the math power method for javascript:

http://www.w3schools.com/jsref/jsref_pow.asp

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yo should do this

var base = 2;
var power = 0;
var answer = 1; 
while ( power < 10 )
{
   answer = answer * 2;
   power = power +  1;  
}

alert(answer);

You have to increment answer otherwise It will always have the same value