How to prevent users from inputting letters or numbers?

Question

I have a simple problem;

Here is the code :

#include
main(){
 int input;
 printf(\"Choose a numeric value\");
 scanf(\"%d\",&input         


        

Answer 1

You should not use scanf to read in numbers - see http://www.gidnetwork.com/b-63.html

Use fgets instead.

However, if you must use scanf, you can do this:

  #include 
  int main() {
      char text[20];
      fputs("enter some number: ", stdout);
      fflush(stdout);
      if ( fgets(text, sizeof text, stdin) ) {
          int number;
          if ( sscanf(text, "%d", &number) == 1 ) {
              printf("number = %d\n", number);
          }
      }
      return 0;
  }