Question

a) Which lines of code contain operations that change the contents of memory in this program?

b) What are those operations?

int main ( void ){

            double dScore1;

            double dScore2;

            double dScore3;

            double dAverage;

            printf("Enter score 1: ");                                             //line 1

            scanf("%lg", &dScore1);                                           //line 2

            printf("Enter score 2: ");                                             //line 3

            scanf("%lg", &dScore2);                                           //line 4

            printf("Enter score 3: ");                                             //line 5

            scanf("%lg", &dScore3);                                           //line 6

            dAverage = (dScore1 + dScore2 + dScore3) / 3.0;    //line 7

            printf("The average is %g\n", dAverage);                 //line 8

            return 0;

}

Answer 1

int main ( void ){

            double dScore1;

            double dScore2;

            double dScore3;

            double dAverage;

            printf("Enter score 1: ");                                             //line 1

            scanf("%lg", &dScore1);                                           //line 2

            printf("Enter score 2: ");                                             //line 3

            scanf("%lg", &dScore2);                                           //line 4

            printf("Enter score 3: ");                                             //line 5

           scanf("%lg", &dScore3);                                           //line 6

            dAverage = (dScore1 + dScore2 + dScore3) / 3.0;    //line 7

            printf("The average is %g\n", dAverage);                 //line 8

            return 0;

}

a) In the above program, line 2 , line 4 and line 6 (marked as green) change the contents of memory.

b) In the scanf() function we are using & (address resolution operator). Now, &dScore1 , &dScore2 and &dScore4 specify the address of dScore1 , dScore2 and dScore3 variables. So, by using scanf() function, user takes the input of dScore1 , dScore2 and dScore3 from the user and store those values in the memory address of dScore1 , dScore2 and dScore3 variables. So, the memory contents of these variables will be changed by these new values (values which are entered by the user as an input).