Scanf

How to ask user to input something

Console Input

The function int scanf(const char*, ...) reads input from the console and stores it in the given variables. To read variables, specify the data type token and provide the address to the variable. The syntax for scanf is similar to printf, but an ampersand (&) is required before the variable name.

#include <stdio.h>

int main() {
    int user_input = 0;
    // enter an integer and press enter
    scanf("%d", &user_input); // your program will be stop here until enter is pressed
    printf("retrieved value: %d", user_input);
    
    return 0;
}

• int scanf(const char *format, ...)

  • const char *format is a pointer to a constant character. For now, don't worry about what a pointer is. You can think of the parameter as requiring a piece of text. For example: "Danny", "%d".

  • ... refers to the variables for storing the information. Due to the nature of C (and because of pointers), you should add & in front of your variables. For example: &GPA.

    • You can pass any number of variables to receive information.

    • e.g. scanf("%d %c %s", &int_input, &char_input, &str_input); accepts "123 a haha" and results in int_input = 123, char_input = 'a', str_input = "haha".

    • Documentation: scanf

Q: What is the use of &?

A: A variable consists of a name, value and address. & returns the address of the variable. This topic (pointers) will be taught in depth in later advanced notes which will not be covered in this tutorial.

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