C中的无限循环不会停止scanf

Question

I started learning C and i am still at simple programs but with a ton of errors :/ The following code once it catches the wrong input (in the else statement) will continue running and it wont stop for the next scan... why is that happening?

const float inch_to_cm = 2.54;

int main()
{
    bool run = true;
    float usr_input;
    while(run){
        printf("Please enter the inches: ");
        if (scanf("%f", &usr_input) == 1){
            printf("Result: %4.2f \n", inch_to_cm*usr_input);
            run = false;
        }
        else{
            printf("I asked for a number!\n");
        }
    }

    return 0;
}

Answer 1

If you are entering anything else than a numerical value then it will not read by scanf and live there for infinite time causing infinite loop. You must have to flush the input buffer. Place this after the else statement:

int c;
while((c = getchar()) != '\n' && c != EOF);