what are format specifiers

it is used during taking input and out put

Int ("%d"): 
Long ("%ld"):
Char ("%c"): 
Float ("%f"): 
Double ("%lf")

example:

char ch = 'd';
double d = 234.432;
printf("%c %lf", ch, d);

char ch;
double d;
scanf("%c %lf", &ch, &d);