1. 7. C program structure

2. 1. Structure of a c program
Any C Program consists of the following parts:
Preprocessor part
Main function. This consists of the following:
The declaration part
The Initialization part
The Input
Processing (Assignment, if/switch, calculations, or any other C statements that will be covered later)
The Output
Return (0) command
This is shown in the diagram of the next slide.
Dr. Soha S. Zaghloul 2

3. 1. Structure of a c program - summarized
Preprocessor part (#include, #define)
Main function
int main (void) {
// declaration part
// initialization part
// input part
// processing
// output
Return (0);
} // end of main function
Dr. Soha S. Zaghloul 3

4. 1.1 declaration part Preprocessor part (#include, #define)
Main function
int main (void) {
// declaration part
int number1, number2, number3;
char gender;
double salary;
// initialization part
// input part
// processing
// output
Return (0);
} // end of main function
Dr. Soha S. Zaghloul 4

5. 1.2 initialization part Preprocessor part (#include, #define)
Main function
int main (void) {
// declaration part
// initialization part
total = 0; // previously declared
double product = 1.0; // undeclared
char name[20] = “xxxxxxxxxxxxxxxx”; //undeclared
// input part
// processing
// output
Return (0);
} // end of main function
Dr. Soha S. Zaghloul 5

6. 1.3 input part Preprocessor part (#include, #define) Main function
int main (void) {
// declaration part
// initialization part
// input part
printf (“Enter the values of three integers\n”);
scanf (“%d%d%d”, &number1, &number2, &number3);
// processing
// output
Return (0);
} // end of main function
Dr. Soha S. Zaghloul 6

7. 1.4 processing part Preprocessor part (#include, #define)
Main function
int main (void) {
// declaration part
// initialization part
// input part
// processing
total = number1 + number2 + number3;
// output
Return (0);
} // end of main function
Dr. Soha S. Zaghloul 7

8. 1.4 processing part (2) Preprocessor part (#include, #define)
Main function
int main (void) {
// declaration part
// initialization part
// input part
// processing
total = total + number1;
product = product * number2;
// output
Return (0);
} // end of main function
Dr. Soha S. Zaghloul 8

9. 1.4 processing part (3) Preprocessor part (#include, #define)
Main function
int main (void) {
// declaration part
// initialization part
// input part
// processing
if (total == 0)
total = total + number1;
else
product = product * number1;
// output
Return (0);
} // end of main function
Dr. Soha S. Zaghloul 9

10. 1.5 output part Preprocessor part (#include, #define) Main function
int main (void) {
// declaration part
// initialization part
// input part
// processing
// output
printf (“Final Results are: “);
printf (“Total = %d, Product = %f”, total, product);
Return (0);
} // end of main function
Dr. Soha S. Zaghloul 10

11. 2. Example (1)
Write a complete program that calculates the average of three integer numbers.
Input?
number1
number2
number3
Type?
integer
value?
Through scanf
Output?
average
Type?
double
value?
To be calculated
// declaration part
int number1, number2, number3;
double average;
// input part
printf (“Enter the values of the three integers: \n”);
scanf (“%d%d%d”, &number1, &number2, &number3);
Dr. Soha S. Zaghloul 11

12. 2. Example (1) – cont’d
Write a complete program that calculates the average of three integer numbers.
#include <stdio.h>
int main (void) {
// declaration part
int number1, number2, number3;
double average;
// input part
printf (“Enter the values of the three integers: \n”);
scanf (“%d%d%d”, &number1, &number2, &number3);
// processing part
average = (number1 + number2 + number3) /3.0;
// output part
printf (“The average equals %f “, average);
return (0);
} // end of main
Dr. Soha S. Zaghloul 12

13. 2. Example (2)
Write a complete program to select an operation based on the value of inventory. Increment total_paper by paper_order if inventory is ‘B’ or ‘C’; increment total_ribbon by ribbon_order if inventory is ‘E’, ‘F’, or ‘D’; increment total_label by label_order if inventory is ‘A’ or ‘X’. Do nothing if inventory is ‘M’. Display an error message if the value of inventory is not one of these eight letters.
input?
inventory
paper_order
ribbon_order
label_order
type?
char
integer
value?
Through scanf
// declaration part
char inventory;
int paper_order, ribbon_order, label_order;
Dr. Soha S. Zaghloul 13

14. 2. Example (2) – cont’d
Write a complete program to select an operation based on the value of inventory. Increment total_paper by paper_order if inventory is ‘B’ or ‘C’; increment total_ribbon by ribbon_order if inventory is ‘E’, ‘F’, or ‘D’; increment total_label by label_order if inventory is ‘A’ or ‘X’. Do nothing if inventory is ‘M’. Display an error message if the value of inventory is not one of these eight letters.
#include <stdio.h>
int main (void) {
// declaration part
char inventory;
int paper_order, ribbon_order, label_order;
// input part
printf (“Enter inventory \n”);
scanf (“%c”, inventory);
Dr. Soha S. Zaghloul 14

15. 2. Example (2) – cont’d
#include <stdio.h>
int main (void) {
Write a complete program to select an operation based on the value of inventory. Increment total_paper by paper_order if inventory is ‘B’ or ‘C’; increment total_ribbon by ribbon_order if inventory is ‘E’, ‘F’, or ‘D’; increment total_label by label_order if inventory is ‘A’ or ‘X’. Do nothing if inventory is ‘M’. Display an error message if the value of inventory is not one of these eight letters.
// declaration part
char inventory;
int paper_order, ribbon_order, label_order;
// input part
printf (“Enter inventory \n”);
scanf (“%c”, inventory);
// iniatlization part
int total_paper = 0;
// processing part
switch (inventory) {
case ‘B’:
case ‘C’: printf (“Enter amount of ordered paper \n”);
scanf (“%d”, &paper_order);
total_paper = total_paper + paper_order;
printf (“Total paper = %d”, total_paper);
break;
Dr. Soha S. Zaghloul 15

16. 2. Example (2) – cont’d
#include <stdio.h>
int main (void) {
Write a complete program to select an operation based on the value of inventory. Increment total_paper by paper_order if inventory is ‘B’ or ‘C’; increment total_ribbon by ribbon_order if inventory is ‘E’, ‘F’, or ‘D’; increment total_label by label_order if inventory is ‘A’ or ‘X’. Do nothing if inventory is ‘M’. Display an error message if the value of inventory is not one of these eight letters.
// declaration part
char inventory;
int paper_order, ribbon_order, label_order;
// input part
printf (“Enter inventory \n”);
scanf (“%c”, inventory);
// iniatlization part
int total_paper = 0, total_ribbon = 0;
// processing part
// continuation of the switch statement
case ‘E’:
case ‘F’:
case ‘D’: printf (“Enter amount of ordered ribbon \n”);
scanf (“%d”, &ribbon_order);
total_ribbon = total_ribbon + paper_order;
printf (“Total ribbon = %d”, total_ribbon);
break;
Dr. Soha S. Zaghloul 16

17. 2. Example (2) – cont’d
#include <stdio.h>
int main (void) {
Write a complete program to select an operation based on the value of inventory. Increment total_paper by paper_order if inventory is ‘B’ or ‘C’; increment total_ribbon by ribbon_order if inventory is ‘E’, ‘F’, or ‘D’; increment total_label by label_order if inventory is ‘A’ or ‘X’. Do nothing if inventory is ‘M’. Display an error message if the value of inventory is not one of these eight letters.
// declaration part
char inventory;
int paper_order, ribbon_order, label_order;
// input part
printf (“Enter inventory \n”);
scanf (“%c”, inventory);
// iniatlization part
int total_paper = 0, total_ribbon = 0, total_label = 0;
// processing part
// continuation of the switch statement
case ‘A’:
case ‘X’: printf (“Enter amount of ordered label \n”);
scanf (“%d”, &label_order);
total_label = total_label + label_order;
printf (“Total label = %d”, total_label);
break;
Dr. Soha S. Zaghloul 17

18. 2. Example (2) – cont’d
#include <stdio.h>
int main (void) {
Write a complete program to select an operation based on the value of inventory. Increment total_paper by paper_order if inventory is ‘B’ or ‘C’; increment total_ribbon by ribbon_order if inventory is ‘E’, ‘F’, or ‘D’; increment total_label by label_order if inventory is ‘A’ or ‘X’. Do nothing if inventory is ‘M’. Display an error message if the value of inventory is not one of these eight letters.
// declaration part
char inventory;
int paper_order, ribbon_order, label_order;
// input part
printf (“Enter inventory \n”);
scanf (“%c”, inventory);
// iniatlization part
int total_paper = 0, total_ribbon = 0, total_label = 0;
// processing part
// continuation of the switch statement
case ‘M’: break;
default: printf (“Invalid input \n”); //invalid inventory value
break;
} // end of switch statement
return (0);
} //end of main
Dr. Soha S. Zaghloul 18

19. 2. Example (2) – cont’d // processing part // Using if statement
if (inventory == ‘B’) || (inventory == ‘C’) {
printf (“Enter amount of ordered paper \n”);
scanf (“%d”, &paper_order);
total_paper = total_paper + paper_order;
printf (“Total paper = %d”, total_paper);
} // (inventory == ‘B’) || (inventory == ‘C’)
else if (inventory == ‘E’) || (inventory == ‘F’) || (inventory == ‘D’)
printf (“Enter amount of ordered ribbon \n”);
scanf (“%d”, &ribbon_order);
total_ribbon = total_ribbon + paper_order;
printf (“Total ribbon = %d”, total_ribbon);
} // (inventory == ‘E’) || (inventory == ‘F’) || (inventory == ‘D’)
else if (inventory == ‘A’) || (inventory == ‘X)
printf (“Enter amount of ordered label \n”);
scanf (“%d”, &label_order);
total_label = total_label + label_order;
printf (“Total label = %d”, total_label);
} // (inventory == ‘A’) || (inventory == ‘X)
else if (inventory != ‘M’) // what if (inventory == ‘M)?
printf (“Invalid Input \n”)
Dr. Soha S. Zaghloul 19

20. 2. Example (3)
The table below shows the normal boiling points of several substances. Write a program that prompts the user for the observed boiling point of a substance in ºC. The program then identifies the substance if the observed boiling point is within 5% (more or less) of the expected boiling point. If the data input is more than 5% higher or lower than any of the boiling points in the table, the program should output the message “Substance unknown”. Substance Expected Boiling Point (ºC) Water 100 Mercury 357 Copper 1187 Silver 2193 Gold 2660
Dr. Soha S. Zaghloul 20

21. 2. Example (3)
The table below shows the normal boiling points of several substances. Write a program that prompts the user for the observed boiling point of a substance in ºC. The program then identifies the substance if the observed boiling point is within 5% (more or less) of the expected boiling point. If the data input is more than 5% higher or lower than any of the boiling points in the table, the program should output the message “Substance unknown”. Substance Expected Boiling Point (ºC) Water 100 Mercury 357 Copper 1187 Silver 2193 Gold 2660
Dr. Soha S. Zaghloul 21

22. 2. Example (3) Input? observed Type? double value? Through scanf
Output?
substance
Type?
string
value?
To be calculated
#include <stdio.h>
int main (void) {
// declaration part
int observed;
char substance[20];
// input part
printf (“Enter the observed boiling point: \n”);
scanf (“%d”, &observed);
return (0);
} // end of main
Dr. Soha S. Zaghloul 22

23. 2. Example (3)
The table below shows the normal boiling points of several substances. Write a program that prompts the user for the observed boiling point of a substance in ºC. The program then identifies the substance if the observed boiling point is within 5% (more or less) of the expected boiling point. If the data input is more than 5% higher or lower than any of the boiling points in the table, the program should output the message “Substance unknown”. Substance Expected Boiling Point (ºC) Water 100 Mercury 357 Copper 1187 Silver 2193 Gold 2660
water_plus5 = (100 * 0.05) + 100;
water_minus5 = (100 * 0.05) – 100;
if (observed >= water_minus5) && (observed <= water_plus5)
strcopy (substance, “water”);
Dr. Soha S. Zaghloul 23

24. 2. Example (3)
The table below shows the normal boiling points of several substances. Write a program that prompts the user for the observed boiling point of a substance in ºC. The program then identifies the substance if the observed boiling point is within 5% (more or less) of the expected boiling point. If the data input is more than 5% higher or lower than any of the boiling points in the table, the program should output the message “Substance unknown”. Substance Expected Boiling Point (ºC) Water 100 Mercury 357 Copper 1187 Silver 2193 Gold 2660
in the same way, calculate:
mercury_plus5, mercury_minus5,
copper_plus5, copper_minus5,
silver_plus5, silver_minus5,
gold_plus5, gold_minus5
Dr. Soha S. Zaghloul 24

25. Don’t forget to declare your variables!!!
2. Example (3)
The table below shows the normal boiling points of several substances. Write a program that prompts the user for the observed boiling point of a substance in ºC. The program then identifies the substance if the observed boiling point is within 5% (more or less) of the expected boiling point. If the data input is more than 5% higher or lower than any of the boiling points in the table, the program should output the message “Substance unknown”. Substance Expected Boiling Point (ºC) Water 100 Mercury 357 Copper 1187 Silver 2193 Gold 2660
Don’t forget to declare your variables!!!
Dr. Soha S. Zaghloul 25

26. Complete the if statement…and conclude your program
2. Example (3)
The table below shows the normal boiling points of several substances. Write a program that prompts the user for the observed boiling point of a substance in ºC. The program then identifies the substance if the observed boiling point is within 5% (more or less) of the expected boiling point. If the data input is more than 5% higher or lower than any of the boiling points in the table, the program should output the message “Substance unknown”. Substance Expected Boiling Point (ºC) Water 100 Mercury 357 Copper 1187 Silver 2193 Gold 2660
Complete the if statement…and conclude your program
Dr. Soha S. Zaghloul 26

27. 2. Example (4)
Write a program that calculates and prints the bill for Riyadh’s power consumption. The rates vary depending on whether the user is residential, commercial, or industrial. A code of R corresponds to a Residential, C corresponds to a Commercial, and I to Industrial. Any other code should be treated as an error. The program should read the power consumption rate in KWH (Kilowatt per Hour); then it calculates the due amount according to the following: The rate is SAR 5 per KWH for Residential, SAR 10 per KWH for Commercial and SAR 20 per KWH for Industrial.
Dr. Soha S. Zaghloul 27

28. 2. Example (4) – input
Write a program that calculates and prints the bill for Riyadh’s power consumption. The rates vary depending on whether the user is residential, commercial, or industrial. A code of R corresponds to a Residential, C corresponds to a Commercial, and I to Industrial. Any other code should be treated as an error. The program should read the power consumption rate in KWH (Kilowatt per Hour); then it calculates the due amount according to the following: The rate is SAR 5 per KWH for Residential, SAR 10 per KWH for Commercial and SAR 20 per KWH for Industrial.
Dr. Soha S. Zaghloul 28

29. 2. Example (4) – input
Write a program that calculates and prints the bill for Riyadh’s power consumption. The rates vary depending on whether the user is residential, commercial, or industrial. A code of R corresponds to a Residential, C corresponds to a Commercial, and I to Industrial. Any other code should be treated as an error. The program should read the power consumption rate in KWH (Kilowatt per Hour); then it calculates the due amount according to the following: The rate is SAR 5 per KWH for Residential, SAR 10 per KWH for Commercial and SAR 20 per KWH for Industrial.
Dr. Soha S. Zaghloul 29

30. 2. Example (4) – output
Write a program that calculates and prints the bill for Riyadh’s power consumption. The rates vary depending on whether the user is residential, commercial, or industrial. A code of R corresponds to a Residential, C corresponds to a Commercial, and I to Industrial. Any other code should be treated as an error. The program should read the power consumption rate in KWH (Kilowatt per Hour); then it calculates the due amount according to the following: The rate is SAR 5 per KWH for Residential, SAR 10 per KWH for Commercial and SAR 20 per KWH for Industrial.
Dr. Soha S. Zaghloul 30

31. 2. Example (4) – processing
Write a program that calculates and prints the bill for Riyadh’s power consumption. The rates vary depending on whether the user is residential, commercial, or industrial. A code of R corresponds to a Residential, C corresponds to a Commercial, and I to Industrial. Any other code should be treated as an error. The program should read the power consumption rate in KWH (Kilowatt per Hour); then it calculates the due amount according to the following: The rate is SAR 5 per KWH for Residential, SAR 10 per KWH for Commercial and SAR 20 per KWH for Industrial.
Dr. Soha S. Zaghloul 31