In C language, when you need to input a three-digit number from the user keyboard and output it in reverse order, you can use the following simple code to achieve this. This code first prompts the user for input, then calculates and formats the output to display the numbers in reverse order. The following are the specific steps:

First, you need to introduce the header file into the C program in order to use the input and output functions. In the main function, define an integer variable x to store the three-digit number entered by the user.

Next, use the printf function to prompt the user to enter a three-digit number, and then use the scanf function to read the user's input and store it in the variable x.

To get the reverse number, you need to perform bitwise operations on x. First, use x%10 to get the ones digit, then x/10%10 to get the tens digit, and finally, x/100 to get the hundreds digit. These operations can be output in the form of %d%d%d through the printf function.

The complete code is as follows:

#include

intmain(){

intx;

printf( "Please enter a three-digit number:");//Prompt user for input

scanf("%d",&x);//Read user input

printf("% d",x%10);//Ones digit

printf("%d",x/10%10);//Tens digit

printf("%d\ n",x/100);//Hundreds digit

return0;

}

This code shows how to implement a simple Reverse function. If you want to know more about C language functions, such as pow10, sqrt, cos, sin and random number generation, you can check the relevant C language function documents, such as Baidu Encyclopedia.