[c-prog] conversion

[suraj_aten]

#include<stdio.h>
#include<conio.h>
main()
{
    int i=57;
    float j=10.98;
    //i=j;
    printf("%d",j);
}
this prog prints a large -ve no...???????

and this one prints NUL
#include<stdio.h>
#include<conio.h>
main()
{
    int i=57;
    float j=10.98;
    //i=j;
    printf("%c",j);
}
why does this happen????????
thanks........