Return values of printf() and scanf() in C/C++

What values do the printf() and scanf() functions return ?

• printf() : It returns total number of Characters Printed, Or negative value if an output error or an encoding error

  Example 1: The printf() function in the code written below returns 6. As ‘CODING’ contains 6 characters.

  // C/C++ program to demonstrate return value // of printf() #include <stdio.h>    int main() {     char st[] = "CODING";        printf("While printing ");     printf(", the value returned by printf() is : %d",                                     printf("%s", st));        return 0; }

  Output: While printing CODING, the value returned by printf() is : 6
  

  Example 2: The printf() function in the code written below returns 9. As ‘123456789’ contains 9 characters.

  // C/C++ program to demonstrate return value // of printf()    #include <stdio.h> int main() {     long int n = 123456789;        printf("While printing ");     printf(", the value returned by printf() is : %d",                                      printf("%d", n));        return 0; }

  Output: While printing 123456789, the value returned by printf() is : 9
  

• scanf() : It returns total number of Inputs Scanned successfully, or EOF if input failure occurs before the first receiving argument was assigned.

  Example 1: The first scanf() function in the code written below returns 1, as it is scanning 1 item. Similarly second scanf() returns 2 as it is scanning 2 inputs and third scanf() returns 3 as it is scanning 3 inputs.

  // C/C++ program to demonstrate return value // of printf()    #include <stdio.h> int main() {     char a[100], b[100], c[100];        // scanf() with one input     printf(" First scanf() returns : %d",                             scanf("%s", a));        // scanf() with two inputs     printf(" Second scanf() returns : %d",                        scanf("%s%s", a, b));        // scanf() with three inputs     printf(" Third scanf() returns : %d",                    scanf("%s%s%s", a, b, c));        return 0; }

  Input:
  Hey!
  welcome to
  geeks for geeks
  Output:
   First scanf() returns : 1
   Second scanf() returns : 2
   Third scanf() returns : 3