C Format Specifiers

Format Specifiers

Format specifiers are used together with the printf() function to tell the compiler what type of data the variable is storing. It is basically a placeholder for the variable value.

A format specifier starts with a percentage sign %, followed by a character.

For example, to output the value of an int variable, use the format specifier %d surrounded by double quotes (""), inside the printf() function:

int myNum = 15;
printf("%d", myNum);  // Outputs 15

To print other types, use %c for char and %f for float:

// Create variables
int myNum = 15;            // Integer (whole number)
float myFloatNum = 5.99;   // Floating point number
char myLetter = 'D';       // Character

// Print variables
printf("%d\n", myNum);
printf("%f\n", myFloatNum);
printf("%c\n", myLetter);

To combine both text and a variable, separate them with a comma inside the
printf() function:

int myNum = 15;
printf("My favorite number is: %d", myNum);

To print different types in a single printf() function, you can use the following:

int myNum = 15;
char myLetter = 'D';
printf("My number is %d and my letter is %c", myNum, myLetter);

Print Values Without Variables

You can also just print a value without storing it in a variable, as long as you use the correct format specifier:

printf("My favorite number is: %d", 15);
printf("My favorite letter is: %c", 'D');

However, it is more sustainable to use variables as they are saved for later and can be re-used whenever.