scanf to enter data from keyboad to C program

We can pass data to our C program by using scanf() function. Once executed our program will wait for the user inputs once it came across any scanf function during program execution. Let us enter an integer value and then display the same value by using printf function.

#include <stdio.h>
int main(void){
int num;
	printf("Enter a number  ");
	scanf("%d",&num);
	printf(" You entered %d", num); // printing outputs
return 0;
}

While using scanf() , before using the variable we will use & ( ampersand ) to indicate to store the data in address of the variable. See the &num to say store the input data in address of our variable num.

As you have seen we will get the same data as output what we enter as input.

Entering more than one data

Using one scanf statement we can ask for more than one data to enter

int main(void){
int num1,num2; // declaring variables as integers
	printf("Enter the  two numbers  ");
scanf("%d %d",&num1,&num2);  // Enter two numbers
printf(" Two numbers are %d,%d  " ,num1, num2); // printng outputs
return 0;
}

Note that after entering first number we have to press Enter and then write the second number.

Reading String data

Here is the code to read string data. Note that scanf function will read until it encounters any space or it reaches its limits.

int main(void){
char name[30];
	printf("Enter your name  ");
	scanf("%s",name);
	printf(" Welcome Mr %30s", name); // printing outputs
return 0;
}

We will read more on scanf in our string handling section for handling other type of data.

%c  - a single character
%d  - a decimal integer 
%e - floating point value
%f - floating point value
%g - floating point value
%h - short integer
%i - floating point value
%o - an octal intger
%s - read a string
%u - unsigned decimal integer
%x - read a hexadecimal integer
%[..] - string of words

With the above list we can prefix these chars in some cases

h for short integers
l for long integers or double
L for long dobule

Example 1: Accepting Integer Input Using scanf()

This example demonstrates how to use scanf() to read an integer input from the user.

#include <stdio.h>

int main() {
    int num;
    printf("Enter an integer: ");
    scanf("%d", &num);
    printf("You entered: %d\n", num);
    return 0;
}

Output:

Enter an integer: 25
You entered: 25

---

Example 2: Accepting Multiple Inputs with scanf()

This example demonstrates how to use scanf() to accept multiple inputs in a single line.

#include <stdio.h>

int main() {
    int age;
    float height;
    
    printf("Enter your age and height: ");
    scanf("%d %f", &age, &height);
    
    printf("You entered - Age: %d, Height: %.2f\n", age, height);
    return 0;
}

Output:

Enter your age and height: 25 5.8
You entered - Age: 25, Height: 5.80

---

Example 3: Reading a Character with scanf()

This example shows how to use scanf() to read a single character input.

#include <stdio.h>

int main() {
    char ch;
    printf("Enter a character: ");
    scanf(" %c", &ch);  // Note the space before %c to handle leftover newlines
    
    printf("You entered: %c\n", ch);
    return 0;
}

Output:

Enter a character: A
You entered: A

---

Example 4: Handling String Input Using scanf()

This example reads a string using scanf() and demonstrates the proper handling of spaces in the input.

#include <stdio.h>

int main() {
    char name[50];
    printf("Enter your name: ");
    scanf("%49s", name);  // Limit input to avoid buffer overflow
    
    printf("Hello, %s!\n", name);
    return 0;
}

Output:

Enter your name: John
Hello, John!

Basic programming structure of C

Basics of C printf() C- Tutorials

Arjun khatiwada	28-01-2013
Plz ,says me limitation of putchar and getchar functions for reading strings

scanf() to input data from keyboard

Entering more than one data

Reading String data

Example 1: Accepting Integer Input Using scanf()

Example 2: Accepting Multiple Inputs with scanf()

Example 3: Reading a Character with scanf()

Example 4: Handling String Input Using scanf()

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