
afdfe6d9385c048c86ecb7213513dee3.ppt
- Количество слайдов: 9
Functions (2) Uni. MAP Sem 2 -10/11 DKT 121: Fundamental of Computer Programming 1
Outline n n n Recall - sample application n functions that return no value n functions that return a value Recall – global variable vs. local variable Pass by value Uni. MAP Sem 2 -10/11 DKT 121: Fundamental of Computer Programming 2
Sample application n Write a C program that reads item code and quantity, then calculate the payment. Use functions: n menu – print item code menu n determine_price – determine price based on item code n calc - calculate payment n print_result – print payment What argument name do I want to feed in as parameters and what to return? ? Uni. MAP Sem 2 -10/11 DKT 121: Fundamental of Computer Programming Think!! Which function return no value and which function return a value. 3
Sample application-cont #include
Sample application-cont void menu( ) { printf("Codet. Itemt. Pricen"); printf("1t. Papayat 1. 00n"); printf("2t. Melont 2. 00n"); printf("3t. Duriant 3. 00n"); printf("t. Otherst 4. 00n"); } float determine_price(int item_code) { float pricing; switch(item_code) { case 1: pricing=1. 00; break; case 2: pricing=2. 00; break; case 3: pricing=3. 00; break; default: pricing=4. 00; } return(pricing); } float calc(float item_price, int quantity) { float answer; answer=item_price*quantity; return(answer); } void print_result(float payment) { printf("Payment is %. 2 fn", payment); } Uni. MAP Sem 2 -10/11 [[email protected] week 5]$ gcc testing. c [[email protected] week 5]$. /a. out Code Item Price 1 Papaya 1. 00 2 Melon 2. 00 3 Durian 3. 00 Others 4. 00 Enter item code and quantity: 1 3 Payment is 3. 00 [[email protected] week 5]$. /a. out Code Item Price 1 Papaya 1. 00 2 Melon 2. 00 3 Durian 3. 00 Others 4. 00 Enter item code and quantity: 9 3 Payment is 12. 00 DKT 121: Fundamental of Computer Programming 5
Global variable vs. local variable modification #include
Pass by Value n n If a parameter is passed by value, then the value of the original data is copied into the function’s parameter (scope: local variable(s)) In other words, it (i. e. local variable) has its own copy of the data changes to copy do not change original data During program execution, it (i. e. local variable) will manipulate the data stored in its own memory space Uni. MAP Sem 2 -10/11 DKT 121: Fundamental of Computer Programming 7
Pass by Value (Example) #include
End Functions (2) Q & A! Uni. MAP Sem 2 -10/11 DKT 121: Fundamental of Computer Programming 9