1. Arrays
C provides the option to the user to combine similar data types into a single entity
It followed contiguous memory allocation
a[0]
a[1]
a[2]
a[3]
a[4]

2. Main () { float avg,sum=0; Int I,a[5]; Printf(“Enter five numbers”); for(i=0;i<5;i++) Scanf(“%d”,&a[i]); Sum=sum+a[i]; avg=sum/5; Printf(“The sum of given number is %f”,sum); Printf(“Average of given number is %f”,avg); }

3. Like normal variable array can also initialized during declaration
example
Int[5]={1,2,3,4,5};
Int[]={1,2,3,4,5};
Float[]={1.0,2.0,3.0,4.0,5.0};

4. Int a[5]={1,2,3,4,5};
Int a[]={1,2,3,4,5}; \\dimensional is optional
Float b[]={1.0,2.0,3.0,4.0,5.0};

5. Array declaration and Initilization
Datatype var_name[size];
The above term is syntax for declaring array
Eg: int b[6];
Float c[6];
Int d[5][5];

6. initialize array in C either one by one or using a single statement
double balance[5] = {1000.0, 2.0, 3.4, 17.0, 50.0};
If you omit the size of the array, an array just big enough to hold the initialization is created.
double balance[] = {1000.0, 2.0, 3.4, 17.0, 50.0};
To assign a single element in array
A[4]=45;

7. Limitation of array a)Static data : Array is static data structure
Memory is allocated during compile time
Once memory is allocated during compile time , it cannot be changed during Run time.

8. b)Can hold the data from the same data type
It cannot hold data from a different data type in a common name
Int a[5]={1,2,3,4.5,6};

9. c)Inserting element is more difficult in array
d)Deleting is not a easy task because the data is stored in contiguous memory allocation
e)Bounds checking:
 It doesnt show error for out of bounds value, instead it will shows the garbage value
f)Shortage of memory: if we don’t know the memory size exactly.
 Memory is allocated during the compile time itself

10. G)Wastage of memory
if array size is too large

11. Multi dimensional array
Its called matrix
Array having more than one subscript
Int a[][];
One subscript value denotes “Row” another subscript value denotes “column”

12. A[0][0]
A[0][1]
A[0][2]
A[1][0]
A[1][1]
A[1][2]
A[2][0]
A[2][1]
A[2][3]

13. Strings
It is a one-dimensional array of characters which is terminated by a null character '\0'.
char greeting[6] = {'H', 'e', 'l', 'l', 'o', '\0'};
the memory presentation string H e l o
‘\0’

14. #include <stdio.h> int main () { char greeting[6] = {'H', 'e', 'l', 'l', 'o', '\0'}; printf("Greeting message: %s\n", greeting ); return 0; }

15. Output:
Hello

16. The following example shows the use of string
#include < stdio.h > main() { char month[15]; printf (”Enter the string”); gets (month); printf (”The string entered is %s”, month); }

17. Reading Strings from the terminal:
char address[15]; scanf(%s,address);

18. String operations 1. Length (number of characters in the string).
2. Concatentation (adding two are more strings)
3. Comparing two strings.
4. Substring (Extract substring from a given string)
5. Copy(copies one string over another)

19. strlen(string);
Strcmp(string1,string2);
Strcmpi(string1,string2); \\not case sens
strcpy(string1,string2);
strlwr(string);
strrev(string);
strcat(string1,string2);
strncmp(string1,string2,length);
strnicmp(string1,stringn,length);
strset(string,symbol);\\replace

20. String constants It is written in pair of double quotas
String is declared as character array
String is not a data type
Single character string doesn’t have the equivalent int value

21. String with single char
String with multiple char
“abg”
String with numbers
“12345”
String with blanks
“india is my country”

22. For example:
‘a’ is not equal to “a”

23. Guess the output

25. 2

26. No Output

27. 3

29. 4

31. 5

33. 6

35. 7

37. 8

38. Output:

39. 9

40. Output

41. 10

50. }

52. string

55. Output
ccccccccccccccccccc

57. Output

59. Output
No output

73. 24