printf: format string + value list

scanf: format string + address list

empty format-string.

The syntax for printf is:

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

Simple usage examples:

1. Print character literal: printf("%c", 'a');

2. Print character variable: printf("%c", my_char);

3. Print string literal: printf("%s", "hello world");

4. Print string variable: printf("%s", my_string);

5. Print integer variable: printf("%d", my_integer);

6. Print floating-point variable: printf("%f", my_float);

%<width>.<precision>f

You can certainly do that ...

printf ("This is a number: 12345\n");

... but that does not have the same value as placing the value in a variable and converting the variable into a string ...

int i = 12345;

printf ("This is a number: %d\n", i);

That's the whole point of format specifiers - to initiate a conversion from one place to another.