Thread: scanf, prevent input letters

Hi, how do i prevent them from entering letters when i ask for numbers, using scanf

also what does this mean

printf ("%d", scanf("%d", &var));

? Does this return 1 if the variable is filled, and 0 if its null?

thanks

Originally Posted by renderstream

Hi, how do i prevent them from entering letters when i ask for numbers, using scanf

You can't do it with scanf alone. A common way to pre process input is to read stdin using fgets, scan the buffer for the expected characters, then call sscanf to put the input into the proper variables, or let the user know they messed up and ask them to try again.

It's a lot of work, and there are easier ways... one reason scanf is seldom used.

-Rog