C printf()

The printf() function is defined in the stdio.h header file. It helps to output the result to the console. It gives formatted output to stdout stream.

int printf(const char *format, ...); #where format can be a integer, character, string, float


printf() Parameters: 

The printf() function takes a format string as a parameter.Format tags prototype is Format tags prototype is %[flags][width][.precision][length]specifier. 

Where specifiers can be - c, d or i, e, E, f, g, G, o, s, u, x, X, P, n, %

Flags can be - +, -, (space), #, 0

Width can be - (number), *

Precision can be - .number, .*

Length can be - h, l, L


Parameter Description Required / Optional
format the string that contains the text to be written to the stdout stream Required
additional arguments containing one value to be inserted instead of each %-tag specified in the format parameter Optional

printf() Return Value

The return value of printf() function is a total number of written characters in success and a negative number on failure.

Input Return Value
If successful, total number of characters
On failure a negative number

Examples of printf() 

Example 1: Working of printf() function in C?

#include <stdio.h>

int main()

    int year = 5;
    float page = 2.1;

    /* Display the results using the appropriate format strings for each variable */
    printf("ontest.com is over %d years old and pages load in %.1f seconds.\n", year, page);

    return 0;


ontest.com is over 5 years old and pages load in 2.1 seconds

Example 2: How printf() works in C?

#include <stdio.h>

int main (){
   char char = 'P';
   char strg[25] = "ontest.com";
   float flt = 8.102;
   int num = 100;
   int no = 150;
   double dble = 15.123456;
   printf("Character is %c \n", char);
   printf("String is %s \n" , strg);
   printf("Float value is %f \n", flt);
   printf("Integer value is %d\n" , num);
   printf("Double value is %lf \n", dble);
   printf("Octal value is %o \n", no);
   printf("Hexadecimal value is %x \n", no);
   return 0;


Character is P
String is ontest.com
Float value is 8.102
Integer value is 100
Double value is 15.123456
Octal value is 226
Hexadecimal value is 96