1. Join to C language
Session 2
By Reza Gholamzadeh st Semester

2. We have an overview to: Anatomy of a C program What is a function?
Declaration of variables
Data types
Choose correct names
Initialize
Assignment
Blocks
Comments
Input and output functions
Conditional statements if
switch
Loops
while
do – while
for
By Reza Gholamzadeh st Semester

3. Preprocess instructions
Anatomy of a C program
Preprocess instructions
Typical C program
Prototypes
Global variables
main() function
function A()
function B()
statements
Declarations
Assignment
Function
Control
null
By Reza Gholamzadeh st Semester

4. What is a function?
A function is a self-contained unit of program code designed to accomplish a particular task
a function can both produce actions (such as procedures) and provide values
they save you from repetitious programming
it makes a program more modular, hence easier to read and easier to change or fix
By Reza Gholamzadeh st Semester

5. Declaration of variables
Declaration structure:
DataType Var1Name = [initialization],[Vare2Name] = [initialization],…;
For example:
int sum = 2;
float avg = 0, var = 1.0;
char mark = ‘A’;
Available data types:
int , char , float , double , long , short , ...
Available names for variables:
The characters at your disposal are lowercase letters, uppercase letters, digits, and the underscore (_)
The first character must be a letter or an underscore
firstName , _sumOf , taxi1 , ...
By Reza Gholamzadeh st Semester

6. Assignment By value By expressions Example: X = 12;
sum = ;
ch = ‘q’;
By expressions
avg = ( a + b + c ) / 3;
x = sin(y);
var1 = var2;
By Reza Gholamzadeh st Semester

7. Blocks A block starts with ‘{‘ and ends with ‘}’
Variables defined in a block , can`t be used outside of the block
Each function have a block
Blocks used for grouping statements
Blocks can be used in blocks
A block: {
statement1;
statement2; … }
By Reza Gholamzadeh st Semester

8. Comments
The parts of the program enclosed in the /* */ symbols are comments
Using comments makes it easier for someone (including yourself) to understand your program
they can be placed anywhere
Everything between the opening /* and the closing */ is ignored by the compiler
use the symbols // to create comments that are confined to a single line
By Reza Gholamzadeh st Semester

9. Input and output functions
Output function printf()
Examples:
printf(“Hello C language!”);
printf(“My name is:\nReza Gholamzadeh”);
printf(“your code is %d”,code);
printf(“\t a + b = %f”,a+b);
Input function scanf()
scanf(“%d”,&input);
scanf(“%f%f%f”,&number1,&number2,&number3);
scanf(“(%d,%d)”,&pointX,&pointY);
By Reza Gholamzadeh st Semester

10. Conditional statements
if statement structures
if (condition)
statement;
if (condition1) {
statement1;
... }
else if(condition2)
else if(condition3) .
else
if (condition) {
statement1;
... }
if (condition)
statement1;
else
statement2;
if (condition) {
statement1;
... }
else
By Reza Gholamzadeh st Semester

11. Conditional statements
switch statement structure
switch (variable) {
case value1:
statement1;
...
break;
case value2:
case value3: .
[default:] }
By Reza Gholamzadeh st Semester

12. Loops while loop structures do – while loop structures
while (condition)
statement;
while (condition) {
statement1;
statement2;
... } do
statement;
while (condition); do {
statement1;
statement2;
... }
while (condition);
By Reza Gholamzadeh st Semester

13. Loops for loop structures for (initializeCounter; condition; step)
statement;
for (initializeCounter; condition; step) {
statement1;
statement2;
... }
By Reza Gholamzadeh st Semester

14. Now ready to write some programs
By Reza Gholamzadeh st Semester

15. Example 1 A program which gets n number and calculates the average.
Output:
Enter value of n: 5
Enter number 1: 6
Enter number 2: 7
Enter number 3: -1
Enter number 4: 16
Enter number 5: -3
Average is: 5.00
By Reza Gholamzadeh st Semester

16. Example 1
#include <stdio.h> int main() { int n,input,sum = 0,i; float avg = 0.0; for(i=0; i<n; i++) printf(“enter number %d: “,i+1); scanf(“%d”,&input); sum+=input; } avg = sum/n; printf(“average is %.2f”,avg); return 0;
By Reza Gholamzadeh st Semester

17. Example 2
A program which gets natural numbers of n and r and calculates the c(n,r).This should include a function to calculate the factorial.
Output:
Enter n and r in format (n,r): (5,3)
Result of c(5,3) is: 10
By Reza Gholamzadeh st Semester

18. Example 2
#include <stdio.h> int fact(int); int main() { int r,n; float c; printf(“enter n and c in (c,r) format: “); scanf(“(%d,%d)”,&n,&r); if(n<r) printf(“incorrect values.”); return 1; } c = fact(n)/(fact(r)*fact(n-r)); printf(“Result of c(%d,%d) is: %f“,n,r,c); return 0;
By Reza Gholamzadeh st Semester

19. Example 2
int fact(int input) { int output = 1 , i; if(input == 0) return 1; for(i = input; i>=1; i--) output *= i; return output; }
By Reza Gholamzadeh st Semester

20. Example 3
A program which gets float point numbers and calculates the minimum & maximum of them.
Output:
Enter value of n: 3
Enter number 1: -1
Enter number 2: 2.5
Enter number 3: 2
Max is 2.50 and min is -1.00
By Reza Gholamzadeh st Semester

21. Example 3
#include <stdio.h> int main() { int n,i; float input,Min,Max; printf(“Enter value of n: “); scanf(“%d”,&n); if(n == 0) return 1; printf(“Enter number 1: “); scanf(“%f”,&input); Max = input; Min = input; for(i = 2; i<=n; i++) if(input < Min) else if(input > Max) } printf(“\nMax is &f and Min is %f”,Max,Min); return 0;
By Reza Gholamzadeh st Semester

22. Example 4
A program which gets three numbers and shows us that numbers can be the lengths of a triangle or not.
Output:
Enter a,b,c in {a,b,c} format: {2,4,3}
Yes.
By Reza Gholamzadeh st Semester

23. Example 4
#include <stdio.h> int main() { int a,b,c; printf(“enter a,b,c in {a,b,c} format: “); scanf(“{%d,%d,%d}”,&a,&b,&c); if(a+b>c && a+c>b && b+c>a) printf(“\nYes.”); else printf(“\nNo.”); return 0; }
By Reza Gholamzadeh st Semester

24. Example 5
A program which gets the coordinatios of vector A & B, and calculate the A*B.
Output:
Enter A in (a,b,c) format: (2,2,3)
Enter A in (d,e,f) format: (1,4,-2)
A*b is: (-16,7,6)
By Reza Gholamzadeh st Semester

25. Example 5
#include <stdio.h> int main() { int a,b,c,d,e,f; printf(“enter A in (a,b,c) format: “); scanf(“(%d,%d,%d)”,&a,&b,&c); printf(“enter B in (d,e,f) format: “); scanf(“(%d,%d,%d)”,&d,&e,&f); printf(“\nA*B is: (%d,%d,%d)”,(b*f-c*e),(c*d-a*f),(a*e-b*d)); return 0; }
By Reza Gholamzadeh st Semester

26. Exercise 1
A program which gets 4 numbers and shows the maximum and minimum of them . This program should include two functions for calculation of maximum and minimum of two numbers.
Output:
Enter numbers: -1 , , 11 , 0
Minimum is and maximum is 12.05)
By Reza Gholamzadeh st Semester

27. Exercise 2
A program which gets a special character and a number (n).It will get other inputs(in character mode) until the nth character of that special character is inputted.
Output:
Enter your character: C
Enter number of repeating: 2
1.Enter character: D
2.Enter character: C
3.Enter character: A
4.Enter character: 5
5.Enter character: C
Program finished after 5 inputs.
By Reza Gholamzadeh st Semester

28. Exercise 3
A program which gets 2 numbers and will show all the prime numbers between these two number .The program should include a function to calculate the prime number.
Output:
Enter A and B: 25 4
Result is: 5,7,11,13,17,19,23
I find 7 prime number between 4 and 25.
By Reza Gholamzadeh st Semester

29. Exercise 4
A program which reads a number in binary base and converts it into decimal base.
Output:
Enter your binary number: 10011
Your number in decimal: 19
By Reza Gholamzadeh st Semester

30. Notes Codes must be executable
Use less variables as you can (the less memory)
Codes should be readable (similar to example’s codes)
Codes should give the right answer (by having bugs, it gets point by the amount of errors)
Must be mailed in the time given( Till 1:00 PM of next Saturday)
By Reza Gholamzadeh st Semester