[Javascript?] Using a function as an argument for another function

mindauggas

Code:

var square = function (x) {
  return x * x;
};

var cube = function (x) {
  return square * x;
};

This is my shot, its not right. Please indicate or suggest the correct answear. :)

Mark44

Quote by mindauggas

Code:

var square = function (x) {
  return x * x;
};

var cube = function (x) {
  return square * x;
};

This is my shot, its not right. Please indicate or suggest the correct answear. :)

No, it's not correct.

Code:

var cube = function (x) {
  return x * square(x);
};

Your thread title is misleading - you aren't using a function as an argument of another function. One function is calling another function. There's a difference.

rcgldr

In C or C++, you can use pointers to functions as arguments:

Code:

#include <stdio.h>

int f1xf2(int (*pf1)(int), int (*pf2)(int), int v){return(pf1(v) * pf2(v));}
int returnv(int v){return(v);};
int square(int v){return(f1xf2(returnv, returnv, v));}
int cube(int v){return(f1xf2(returnv, square, v));}
int quad(int v){return(f1xf2(square, square, v));}

int main(int argc, char ** argv)
{
    printf("square 2 = %3d\n", square(2));
    printf("cube   3 = %3d\n", cube(3));
    printf("quad   4 = %3d\n", quad(4));
    return(0);
}

gsal

I am confused...it always bugs me when people do not state what language they are talking about...sure, if I knew, I would recognize it; but often times I don't and I can still help, if I knew what to google.

So, the last post is C, sure...what's the first one, too? or is it matlab?

Mark44

Looks like JavaScript to me.

mindauggas

Sorry, it's JavaScript

mindauggas

Once again, sorry. This time for abandoning my own topic. Like I said the programming language is JavaScript. And yes, thanks for pointing out, that the title is misleading: the function is indeed calling another function, not using it as an argument.

Returning to the problem. "When we call the square function as a part of the cube function, we still have to define the parameter associated with the square function" - a hint provided says thus. But how to write this assignment? I have never assigned a parameter for a function in the body of another function.

Any hints?
Should I assign a parameter the same way as a variable?

gsal

These kind of simple questions is something you don't need a forum for...you can play around with the language and its compiler/interpreter and test stuff at will...it does not cost any money and you are not going to break anything...play around, experiment!

...if, on the other hand, you have a major logic problem or a bug that you cannot find...then, the forum could help.

gabbagabbahey

Quote by mindauggas

Returning to the problem. "When we call the square function as a part of the cube function, we still have to define the parameter associated with the square function" - a hint provided says thus. But how to write this assignment? I have never assigned a parameter for a function in the body of another function.

Any hints?
Should I assign a parameter the same way as a variable?

Can you state the original problem/assignment as it is given to you?

DavidSnider

Using a function as an argument to another function would work like this:

Code:

var square = function(x) { return x * x; }
var cube = function(f,x) { return x * f(x); }

cube(square,2);

Though in this context I don't know why you'd want to pass in a function. I don't imagine you'd ever be swapping it out.

mindauggas

Quote by DavidSnider

Using a function as an argument to another function would work like this:

Code:

var square = function(x) { return x * x; }
var cube = function(f,x) { return x * f(x); }

cube(square,2);

Though in this context I don't know why you'd want to pass in a function. I don't imagine you'd ever be swapping it out.

Thanks, this solved it.

Code:

var square = function (x) {
  return x * x;
};

var cube = function (x) {
  return square(x) * x;
};

The answer to your question: it just for the sake of knowing how to use functions in all/allmost alt the ways legitimate.

rcgldr

I thought the idea was to use functions as parameters to other functions. I'm not sure if this syntax is correct for javascript, but it should look something like this:

Code:

var f1xf2 = function(f1, f2, x) {return f1(x) * f2(x);}
var returnx = function(x) {return x;}
var square = function(x) {return x * x;}
var cube = function(x) {return f1xf2(returnx, square, x);}

mindauggas

Quote by rcgldr

I thought the idea was to use functions as parameters to other functions. I'm not sure if this syntax is correct for javascript, but it should look something like this:

Code:

var f1xf2 = function(f1, f2, x) {return f1(x) * f2(x);}
var returnx = function(x) {return x;}
var square = function(x) {return x * x;}
var cube = function(x) {return f1xf2(returnx, square, x);}

The original title probably mislead you, I apologize for this. the title should have stated that one function calls another function :)

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mindauggas	[Javascript?] Using a function as an argument for another function Tweet Code: var square = function (x) { return x * x; }; var cube = function (x) { return square * x; }; This is my shot, its not right. Please indicate or suggest the correct answear. :)

gsal	[Javascript?] Using a function as an argument for another function I am confused...it always bugs me when people do not state what language they are talking about...sure, if I knew, I would recognize it; but often times I don't and I can still help, if I knew what to google. So, the last post is C, sure...what's the first one, too? or is it matlab?

DavidSnider Recognitions: Gold Member	Using a function as an argument to another function would work like this: Code: var square = function(x) { return x * x; } var cube = function(f,x) { return x * f(x); } cube(square,2); Though in this context I don't know why you'd want to pass in a function. I don't imagine you'd ever be swapping it out.

rcgldr Recognitions: Homework Help	I thought the idea was to use functions as parameters to other functions. I'm not sure if this syntax is correct for javascript, but it should look something like this: Code: var f1xf2 = function(f1, f2, x) {return f1(x) * f2(x);} var returnx = function(x) {return x;} var square = function(x) {return x * x;} var cube = function(x) {return f1xf2(returnx, square, x);}