what is the function of getch() in c programming?

It is a predefined function in "conio.h" (console input output header file) will tell to the console wait for some time until a key is hit given after running of program.

By using this function we can read a character directly from the keyboard. Generally getch() are placing at end of the program after printing the output on screen.
Example :
#include
#include

void main()
{
int a=10, b=20;
int sum=0;
clrscr();
sum=a+b;
printf("Sum: %d",s);
getch(); // use getch() befor end of main()
}

Output:
Sum: 30