double and float array type

[a.mlw.walker]

Hi Guys,
So i am using a loop to fill an array from user input.
Whats the difference between a float and a double because I am not worried:

double init_T[4]={0};
	for (i = 0; i <= 4; i++)
	{
	    //init_T[i] = i+2;
	    scanf("%f",&init_T[i]);
	}
	for (i = 0; i <= 4; i++)
	{
	    printf("%f\n",init_T[i]);
	}

Input 1 2 3 4 5
Output
1
2
3
4
5
then change the array to a type double and Output becomes:
0.00
0.00
0.00
0.00
0.56556
Why does the double change everything?

[grumpy]

A double is larger than a float, so needs a different format for scanf() - it is rather critical that scanf() know the actual size of the variable being read. %f is for float. This needs to be modified with a l (letter L) prefix for double (i.e. %lf). The prefix is also need for other floating point formats (%e versus %le, %g versus %lg, etc).

The l modifier is not required for printf() when printing floating point types (as a float value is implicitly promoted to double when passed by value).

If you want to work with long double types, then the L format specifier is needed for both scanf() and printf() - %Le, %Lf, %Lg.