Input error

[mfantastique]

This must be one of those things that people mess up on when they're tired o_o. Please help me find what's wrong with the following code:

#include <stdio.h>

double pow(double base, int exp);
int factorial(int num);

main()
{
    int n = 1;
    double term = 1, approximation = 1, exp;

    printf("Approximate e^x. x: ");
    scanf("%f", &exp);
    printf("EXP is %f\n", exp);

    getchar();
}

double pow(double base, int exp)
{
	int i;
	double product = 1;
	if(base == 0)
		return 0;
	for(i = 0; i < exp; i++)
		product *= base;
	return product;
}

int factorial(int num)
{
	int i, product = 1;
	if(num == 0)
		return 0;
	for(i = 2; i <= num; i++)
		product *= i;
	return product;
}

Thanks.

[bithub]

First of all, main() should return an int. Second of all, to get the user to input a double, you need to do:

scanf("%lf",%exp);

[xErath]

you're not calling pow nor factorial from anywhere....
and

 scanf("%lf", &exp);
printf("EXP is %lf\n", exp);

The same as bithub posted , but don't forget also the printf! float and double have different representations in memory.

[bithub]

actually printf("%f",exp) is exactly the same as printf("%lf",exp).

[Dave_Sinkula]

actually printf("%f",exp) is exactly the same as printf("%lf",exp).

Except that behavior is undefined prior to C99.

[bithub]

I see nothing wrong with following the newest standard. Especially considering it's been out for over 5 years now.

[Prelude]

>I see nothing wrong with following the newest standard.
It's best to limit yourself to a subset of features common to both standards until the new standard is widely implemented. This is especially important where a new standard feature is undefined behavior in the old standard.

>Especially considering it's been out for over 5 years now.
I use a state of the art compiler, but it doesn't compile C99. Just because the standard has been out for over five years doesn't mean that compilers will support it. In your work, feel free to use whatever you want; here, we assume C89 and stick with the common subset unless there's a strong reason not to.

[bithub]

I use a state of the art compiler, but it doesn't compile C99

Just out of curiousity, what compiler do you use?

[caroundw5h]

you prolly want another getchar() in there too, if you want to see what the result is. as it stands, scanf has input when you press enter. so its going to close most likely.
Also on the nitpicky tip, Main has no arguments so it should be

int main(void)

[Prelude]

>Just out of curiousity, what compiler do you use?
Visual C++ .NET, primarily. Though I also make use of others, not nearly as much though.

>Also on the nitpicky tip
Getting really nitpicky, both versions are valid because main is a function definition, not a declaration. In a function definition, an empty parameter list does indeed mean "no arguments". As a stylistic issue, void should be used to maintain consistency with other functions that do have a declaration (in which case, void is required or the compiler will assume a K&R style function declaration, which is bad).

Personally, I'd be more worried about the very real issue of undefined behavior from not returning a value rather than a style issue.