启动C程序时出现问题

Question

I'm trying to execute the code below. However, in eclispe, the program doesn't start until I enter a character and press enter. For instance, if I hit run, I have to enter the number that will represent the age before it even asks me to enter my age. I am wondering how to fix this.

int main() {

        int age;                          /* Need a variable... */

        printf( "Please enter your age" );  /* Asks for age */
        scanf( "%d", &age );                 /* The input is put in age */
        if ( age < 100 ) {                  /* If the age is less than 100 */
            printf ("You are pretty young!\n" ); /* Just to show you it works... */
        }
        else if ( age == 100 ) {            /* I use else just to show an example */ 
            printf( "You are old\n" );       
        }
        else {
            printf( "You are really old\n" );     /* Executed if no other statement is */
        }
        return 0;
}

Answer 1

This is a pretty classic problem. Your output stream has not been flushed. Usually this happens after writing a newline (which you are not doing). If you don't want a newline, you could issue a hard flush on standard out:

printf( "Please enter your age" );
fflush( stdout ); 
scanf( "%d", &age );

While I'm here, can I ask that you think about your commenting style? Commenting every line of code is excessive. Anybody who can read code understands what each line does, without needing a comment. Put comments on their own line, and only to give an overview of several lines of code. I prefer to see a quick overview of what I'm about to read so I know whether to bother reading it or not.