Add this line in the beginning of your code #include<stdio.h> to include standard input output header file.
Use scanf() functionin your code as mentioned below, Here %d is format specifier for integer data type and & is ampersand operator. Whatever integer as a input would be given by the user will be stored where ? answer to this question is given by ‘&’, it specifies the address where the user input is to be stored.
To see what user input was use printf() function.
Now open the command prompt to compile the program using command – gcc file_name.c
Then a executable file will be generated, just mention its name(in my case it was ‘a’).
Then it will ask for user input which is indicated by blinking underscore. Give your input and press ENTER.