Thread: So another simple program just help me with this logic

Code:

#include <stdio.h>


int main ()
{
    int day = 1;
    float amount = .01;


    while (day <= 31){
        printf ("Day:%d \t Amount:$%.2f\n", day, amount);
        amount *= 2;
        day++;
    }
    printf ("-----------------------------------------------------------\n");


    day = 1;
    amount = .01;
    while (day <= 31){
        printf ("Day:%d \t Amount:$%.2f\n", day, amount);
        amount * 2;
        day++;
    }
    return 0;
}

So yeah it's two kind of examples. Just curious about the logic behind

Code:

amount *= 2;

and

Code:

amount * 2;

Why did it not multiply in the 2nd while loop while in the first it multiplied. I mean it's somewhat the same right? What amount *= 2 is saying to amount * 2? Just confused.

Originally Posted by laserlight

Recall that:

Code:

amount *= 2;

is logically equivalent to:

Code:

amount = amount * 2;

So amount * 2 is just multiplying the variable right? Or no? I jsut dont get it.

Thanks that helped bro! Alright new thread XD