basic c question

#include <stdio.h>

int main ()
{
/* local variable definition */
int a = 100;

/* check the boolean condition /
if( a < 20 )
{
/
if condition is true then print the following /
printf(“a is less than 20\n” );
}
else
{
/
if condition is false then print the following */
printf(“a is not less than 20\n” );
}
printf(“value of a is : %d\n”, a);

return 0;
}

im really struggling to understand %d and how its used could someone please explain please thank you

You mean "sprintf" - Arduino doesn't have "printf".
"%d" simply means print the decimal value of the supplied parameter, in this case the value of the variable "a".

Please remember to use code tags.

im really struggling to understand %d

%d is a format specifier. It says that the variable is to be treated as an int, and output accordingly. Format specifiers can get a lot more complicated, and can add leading spaces, zeros, signs, etc. as well as control width (never less than n characters, for instance).

and how its used

It's only used in calls to functions that expect format specifiers, like printf().

hay thank you i now understand now