C User Input
User Input
You have already learned that printf() is used to output values in C.
To get user input, you can use the scanf() function:
Example
Output a number entered by the user:
// Create an integer variable that will store the number we get from the user
int myNum;
// Ask the user to type a number
printf("Type a number:
\n");
// Get and save the number the user types
scanf("%d", &myNum);
// Output the number the user typed
printf("Your number is: %d", myNum);
Run example »
The scanf() function takes two arguments: the format specifier of the variable (%d in the example above) and the
reference operator (&myNum), which stores the memory address of the variable.
Tip: You will learn more about memory addresses and functions in the next chapter.
User Input Strings
You can also get a string entered by the user:
Example
Output the name of a user:
// Create a string
char firstName[30];
// Ask the user to input some
text
printf("Enter your first name: \n");
// Get and save the text
scanf("%s", firstName);
// Output the text
printf("Hello %s.",
firstName);
Run example »
Note that you must specify the size of the string/array (we used a very high
number, 30, but atleast then we are certain it will store enough characters for the first name), and you don't have to specify the
reference operator (&) when working with strings in scanf().
