What do I use for Pi?

[ssnapier]

I am working on a homework assignment and I have to use Pi as part of a formula. Is there something built in to stdio for Pi or should I just make a float variable out to 4 or 5 decimals and call it a night?

[CommonTater]

Just define a constant... #define pi = 3.1415 ... to whatever depth you need.

[itCbitC]

Include the "math.h" header file and use the symbol M_PI.

[ssnapier]

I used this... good?

const float PI=3.141593

[CommonTater]

I used this... good?

const float PI-3.141593

Ummm no ... you don't want a - sign in there, you want an = sign. Otherwise, no problem.

[ssnapier]

I realized the typo as soon as I posted it, and edited... I also used the semicolon at the end, but thanks!

[brewbuck]

Include the "math.h" header file and use the symbol M_PI.

While that works on a lot of compilers, it's actually isn't standard.

Yes, I was also amazed upon learning it.

The old-school way of getting pi is to compute it at runtime by taking the arctan of 1 then multiplying by 4:

const double pi = 4.0 * atan(1.0);