C coding to print the value until next Key Stock?

Here i need to get Keybaord input but process should not wait for keybaord input
whenever Key is pressed corresonding action should take place

eg. if first time i pressed '+' the i value should be incremented until
next key is pressed and if '-' is pressed then i value should be decremented
until next key is pressed. pls refer & check complete the following code.

void main()
{
int i=0;
char ch='*';
while(1)
{
/* Here i need to get Keybaord input but process should not wait for keybaord input
whenever Key is pressed corresonding action should take place

eg. if first time i pressed '+' the i value should be incremented until
next key is pressed and if '-' is pressed then i value should be decremented
until next key is pressed.

*/
KeyInput = ReadKeybaordInput();

if(KeyInput == '+')
printf("\n i=%d",i++);
else if(KeyInput == '-')
printf("\n i=%d",i--);
else if(KeyInput == '*')
printf("\n i=%d",i);
else if(KeyInput == '/')
exit(0);

}
}