scanf in C

In C programming language, scanf is a function that stands for Scan Formatted String. It reads data from stdin (standard input stream i.e. usually keyboard) and then writes the result into the given arguments.

• It accepts character, string, and numeric data from the user using standard input.
• Scanf also uses format specifiers like printf.

Syntax:

int scanf( const char *format, … );

Here,

• int is the return type.
• format is a string that contains the type specifiers(s).
• “…” indicates that the function accepts a variable number of arguments.

Example type specifiers recognized by scanf:

%d to accept input of integers.

%f to accept input of real number.

%c to accept input of character types.

%s to accept input of a string.

Example:

int var;
scanf(“%d”, &var);

The scanf will write the value input by the user into the integer variable var.

Return Values:

>0: The number of values converted and assigned successfully.

  0: No value was assigned.

<0: Read error encountered or end-of-file(EOF) reached before any assignment was made.

Why &?

While scanning the input, scanf needs to store that input data somewhere. To store this input data, scanf needs to known the memory location of a variable. And here comes the ampersand to rescue.

• & is also called as address of the operator.
• For example, &var is the address of var.

Below is the C program to implement scanf:

C

// C program to implement
// scanf
#include <stdio.h>

// Driver code
int main()
{
    int a, b;

      printf("Enter first number: ");
      scanf("%d", &a);

      printf("Enter second number: ");
      scanf("%d", &b);

      printf("A : %d \t B : %d" ,
            a , b);

    return 0;
}

Output:

Enter first number: 5
Enter second number: 6
A : 5      B : 6

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