Question

Couldnt understand how numbers are handled in C. Could anyone point to a good tutorial.

#include<stdio.h>
main()
{
    printf("%f",16.0/3.0);
}

This code gave: 5.333333

But

#include<stdio.h>
main()
{
    printf("%d",16.0/3.0);
}

Gave some garbage value: 1431655765

Then

#include<stdio.h>
main()
{
    int num;
    num=16.0/3.0;
    printf("%d",num);
}

Gives: 5

Then

#include<stdio.h>
main()
{
    float num;
    num=16/3;
    printf("%f",num);
}

Gives: 5.000000

Answer 1

printf is declared as

int printf(const char *format, ...);

the first arg (format) is string, and the rest can be anything. How the rest of the arguments will be used depending on the format specifiers in format. If you have:

printf("%d%c", x, y);

x will be treated as int, y will be treated as char.
So,

 printf("%f",16.0/3.0);

is ok, since you ask for float double (%f), pass float double(16.0/3.0)

printf("%d",16.0/3.0);

you ask for int(%d), you pass float double (double and int have different internal representation) so, the bit representation of 16.0/3.0 (double) corresponds to bit representation of 1431655765(int).

 int num;
 num=16.0/3.0;

compiler knows that you are assigning to int, and converts it for you. Note that this is different than the previous case.