Printf

Indeed, printf() is not a standalone function — it's a part of a broader family of functions. This family includes sprintf(), vprintf(), vsprintf(), and vfprintf(). However, for the purposes of our introductory course, we'll focus solely on printf().

Take a look at a typical usage of the printf() function:

Main


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#include <stdio.h>

int main()
{
	int iVariable = 832; // declaring and initialization int type variable

	printf("iVariable = %d \n", iVariable) ; // ???

	return 0;
}

The output can be broken down into two main parts:

The format string;
The data to be displayed.

The data to be displayed is straightforward — it's just the variable we're working with. But let's delve deeper into the format string.

Format String

C language doesn't inherently possess Input/Output (I/O) capabilities. The role of the printf() function is to take your variable's value, convert its content into characters, and then replace the "%d" with them.

Format Specifiers

The %d in our format string is what's called a format specifier.

Format specifiers indicate the type of data that should be displayed within the format string, serving as a heads-up of sorts. In our scenario, the specifier alerts the function to expect integer data. Throughout this course, we'll touch on a few of these specifiers, such as:

%d – for integers;
%f – for floating-point numbers;
%c - for single characters.

Note
The application of various format specifiers will hinge on your experience with C programming.

This concept aligns with the example we reviewed in the previous lesson:

Main


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#include <stdio.h>

int main()
{
	int iVariable = 832; // variable of int type
	float fVariable = 54.984; // variable of float type
	char cVariable = '#'; // variable of char type

	printf("iVariable = %d \n", iVariable); // using %d for integer
	printf("fvariable = %f \n", fVariable); // using %f for float
	printf("cVariable = %c \n", cVariable); // using %c for single character
}

Note
Remember, "\n" is a control character that moves subsequent content to a new line.

One of the great things about the printf() function is its ability to print multiple variables simultaneously!

main


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#include <stdio.h>

int main()
{
	int iVariable = 832; 
	float fVariable = 54.984; 
	char cVariable = '#'; 

	printf(" iVariable = %d \n fvariable = %f \n cVariable = %c \n", iVariable, fVariable, cVariable); 

	return 0;
}

Here, the format specifiers and the variables are paired in sequence:

However, if you mismatch the specifier, your program will not display the data correctly:

Main


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# include <stdio.h>

int main()
{
  	int iVariable = 1234;
  
	printf("%f", iVariable); // %f - a floating point number for floats

 	return 0;
}

Everything was clear?

Section 2. Chapter 3