The document provides information about arrays, strings, and character handling functions in C language. It discusses: 1. Definitions and properties of arrays, including declaring, initializing, and accessing single and multi-dimensional arrays. 2. Built-in functions for testing and mapping characters from the ctype.h library, including isalnum(), isalpha(), iscntrl(), isdigit(), ispunct(), and isspace(). 3. Strings in C being arrays of characters terminated by a null character. It discusses common string handling functions from string.h like strlen(), strrev(), strlwr(), strupr(), strcpy(), strcat(), and strcmp().

1. D.E.I. TECHNICAL COLLEGE
COURSE TITLE: Software Development-VI
SLIDE-2
COURSE CODE: VIT351
CLASS: DIPLOMA IN INFORMATION TECHNOLOGY VOCATIONAL (1ST YEAR)
SESSION: 2019-20

2. TOPICS COVERED
 ARRAYS IN C
 MULTIDIMENSIONAL ARRAYS
 CHARACTER HANDLING IN C
 STRING HANDLING IN C
 QUIZ SET 2

4. What is an Array?
 Arrays are the collection of a finite number of homogeneous
data elements.
 Elements of the array are referenced respectively by an
index set consisting of n consecutive numbers and are
stored respectively in successive memory locations.
 The number n of elements is called the length or size of the
array.
GO TO TOPICS

5. Continue….
 Array is a collection of similar elements. These similar elements
could be all ints, floats, doubles, chars, etc. Array is also known as
subscript variable.
 Array can store a fixed-size sequential collection of elements of
the same type.
 Array elements are stored in contiguous memory block.
 Instead of declaring individual variables, such as number0,
number1, ..., and number99, you can declare one array variable.
 Creating array is creating a group of variables and all its elements
are accessed via single name and different subscript values.

6. Properties of an Array
1) Indexing of an array begins from zero (0).
2) The variable name of array contains the base address of
the memory block.
3) The array variable are created at the time of
compilation.
4) The size of the array cannot be altered at runtime.

7. How to declare an Array?
Syntax:
dataType arrayName[arraySize];
For example,
float mark[5];
This is called single dimensional array.
Here, we declared an array, mark, of floating-point type.
And its size is 5. Meaning, it can hold 5 floating-point values.
It's important to note that the size and type of an array cannot
be changed once it is declared.

8.  Array declaration by specifying size
// Array declaration by specifying size
int arr1[10];
// With recent C/C++ versions, we can also
// declare an array of user specified size
int n = 10;
int arr2[n];
 Array declaration by initializing elements
// Array declaration by initializing elements
int arr[] = { 10, 20, 30, 40 }
// Compiler creates an array of size 4.
// above is same as "int arr[4] = {10, 20, 30, 40}"
 Array declaration by specifying size and
initializing elements
// Array declaration by specifying size and
initializing elements
int arr[6] = { 10, 20, 30, 40 }
// Compiler creates an array of size 6,
initializes first
// 4 elements as specified by user and rest
two elements as 0.
// above is same as "int arr[] = {10, 20, 30, 40,
0, 0}"

9. How to access an Array?
 Array elements are accessed by using an integer index.
 Index of an array starts from 0 to size-1 i.e first element of arr array will be stored at arr[0]
address.
Example:
#include <stdio.h>
int main()
{
int arr[5];
arr[0] = 5;
arr[2] = -10;
arr[3 / 2] = 2; // this is same as arr[1] = 2
arr[3] = arr[0];
printf("%d %d %d %d", arr[0], arr[1], arr[2], arr[3]);
return 0;
}

10. Initialization of an Array
 After an array is declared it must be initialized. Otherwise, it will
contain garbage value(any random value). An array can be initialized at either compile
time or at runtime.
data-type array-name[size] = { list of values };
/* Here are a few examples */
int marks[4]={ 67, 87, 56, 77 }; // integer array initialization
float area[5]={ 23.4, 6.8, 5.5 }; // float array initialization
int marks[4]={ 67, 87, 56, 77, 59 }; // Compile time error
In such case, there is no requirement to define the size. So it may also be written as the
following code.
int marks[]={20,30,40,50,60};

11. Example:
#include <stdio.h>
int main()
{
int marks[10], i, n, sum = 0, avg;
printf("Enter number of elements: ");
scanf("%d", &n);
for(i=0; i<n; i++)
{
printf("Enter number");
scanf("%d", &marks[i]);
// adding integers entered by the user to the sum variable
sum =sum+marks[i];
}
avg = sum/n;
printf("Average = %d", avg);
return 0;
}

12. Multi-dimensional Array
 C language supports multidimensional arrays also.
 The simplest form of a multidimensional array is the two-dimensional array.
 Both the row's and column's index begins from 0.
Declaration:
data-type array-name[row-size][column-size]
/* Example */
int a[3][4];
GO TO TOPICS

13. Initialization of 2-D Array
 int b[2] [3] = {12,65,78,45,33,21}; //valid
 int b[ ] [3] = {12,65,78,45,33,21}; // valid
 int b[2] [ ] = {12,65,78,45,33,21}; //invalid
 int b[ ] [ ] = {12,65,78,45,33,21}; // invalid

14. Example: Adding two matrices
#include <stdio.h>
int main()
{ int i,j;
int a[2][2], b[2][2], result[2][2];
// Taking input using nested for loop
printf("Enter elements of 1st matrixn");
for (i = 0; i < 2; i++)
for (j = 0; j < 2; j++){
printf("Enter a%d%d: ", i + 1, j + 1);
scanf("%d", &a[i][j]); }
// Taking input using nested for loop
printf("Enter elements of 2nd matrixn");
for (i = 0; i < 2; i++)
for (j = 0; j < 2; j++){
printf("Enter b%d%d: ", i + 1, j + 1);
scanf("%d", &b[i][j]);
}
// adding corresponding elements of two arrays
for (i = 0; i < 2; i++)
for (j = 0; j < 2; j++)
{
result[i][j] = a[i][j] + b[i][j];
}
// Displaying the sum
printf("nSum Of Matrix:n");
for (i = 0; i < 2; i++)
for (j = 0; j < 2; j++)
{
printf("%dt", result[i][j]);
if (j == 1)
printf("n");
}
return 0;
}

15. Important Note:
 The array elements can be accessed in a constant time by using the index of the
particular element.
 To access an array element, address of an element is computed as an offset
from the base address of the array and one multiplication is needed to compute
what is supposed to be added to the base address to get the memory address
of the element
 First the size of an element of that data type is calculated and then it is multiplied
with the index of the element to get the value to be added to the base address.
 This process takes one multiplication and one addition. Since these two
operations take constant time, we can say the array access can be performed
in constant time.

17. Dealing with Characters
ctype.h file includes functions that are useful for testing and
mapping characters.
All the functions defined in ctype.h accept int as a
parameter, whose value must be EOF or representable as
an unsigned char.
These functions return non-zero (true) if the argument
satisfies the condition described else the functions return
zero (false).
GO TO TOPICS

18. isalnum() Function
 Description
The C library function void isalnum(int c) checks if the passed
character is alphanumeric.
 Declaration
int isalnum(int c);
 Parameters
c − This is the character to be checked.
 Return Value
This function returns non-zero value if c is a digit or a letter, else it
returns 0.

19. Example:1#include <ctype.h>
#include<stdio.h>
int main () {
int var1 = 'a';
int var2 = '4';
int var3 = 't';
if( isalnum(var1) ) {
printf("var1 = |%c| is alphanumericn", var1 );
} else {
printf("var1 = |%c| is not alphanumericn", var1 ); }
if( isalnum(var2) ) {
printf("var2 = |%c| is alphanumericn", var2 );
} else {
printf("var2 = |%c| is not alphanumericn", var2 ); }
if( isalnum(var3) ) {
printf("var3 = |%c| is alphanumericn", var3 );
} else {
printf("var3 = |%c| is not alphanumericn", var3 ); }
return(0); }

20. isalpha() Function
 Description
The C library function void isalpha(int c) checks if the passed
character is alphabet.
 Declaration
int isalpha(int c);
 Parameters
c − This is the character to be checked.
 Return Value
This function returns non-zero value if c is a letter, else it returns 0.

21. Example:2#include <stdio.h>
#include <ctype.h>
int main () {
int var1 = 'a';
int var2 = '4';
int var3 = 't';
if( isalpha(var1) ) {
printf("var1 = |%c| is an alphabetn", var1 );
} else {
printf("var1 = |%c| is not an alphabetn", var1 );}
if( isalpha(var2) ) {
printf("var2 = |%c| is an alphabetn", var2 );
} else {
printf("var2 = |%c| is not an alphabetn", var2 );}
if( isalpha(var3) ) {
printf("var3 = |%c| is an alphabetn", var3 );
} else {
printf("var3 = |%c| is not an alphabetn", var3 );}
return(0); }

22. iscntrl() Function
 Description
The C library function void iscntrl(int c) checks if the passed character
is a control character.
 Declaration
int iscntrl(int c);
 Parameters
c − This is the character to be checked.
 Return Value
This function returns non-zero value if c is a control character, else it
returns 0.

23. Example:3#include <stdio.h>
#include <ctype.h>
int main ()
{
int i = 0, j = 0;
char str1[] = "We like to learn a about t programming";
char str2[] = "these tutorials n are nice";
/* Prints string till control character a */
while( !iscntrl(str1[i]) )
{
putchar(str1[i]);
i++;
}
/* Prints string till control character n */
while( !iscntrl(str2[j]) )
{
putchar(str2[j]);
j++;
}
return(0);
}

24. isdigit() Function
 Description
The C library function void isdigit(int c) checks if the passed
character is a decimal digit character.
Decimal digits are (numbers) − 0 1 2 3 4 5 6 7 8 9.
 Declaration
int isdigit(int c);
 Parameters
c − This is the character to be checked.
 Return Value
This function returns non-zero value if c is a digit, else it returns 0.

25. ispunct() Function
 Description
The C library function int ispunct(int c) checks whether the passed
character is a punctuation character. A punctuation character is
any graphic character (as in isgraph) that is not alphanumeric (as
in isalnum).
 Declaration
int ispunct(int c);
 Parameters
c − This is the character to be checked.
 Return Value
This function returns a non-zero value(true) if c is a punctuation
character else, zero (false).

26. isspace() Function
 Description
The C library function int isspace(int c) checks whether the passed character is white-
space.Standard white-space characters are:
 ' ' (0x20) space (SPC)
 't' (0x09) horizontal tab (TAB)
 'n' (0x0a) newline (LF)
 'v' (0x0b) vertical tab (VT)
 'f' (0x0c) feed (FF)
 'r' (0x0d) carriage return (CR)
Declaration
int isspace(int c);
Parameters
c − This is the character to be checked.
Return Value
This function returns a non-zero value(true) if c is a white-space character else, zero (false).

27. String Handling in C
 String is a sequence of characters that is treated as a single data item and terminated by
null character '0'.
 Remember that C language does not support strings as a data type.
 A string is actually one-dimensional array of characters in C language.
 These are often used to create meaningful and readable programs.
 C language supports a large number of string handling functions that can be used to
carry out many of the string manipulations. These functions are packaged
in string.h library.
char name[12] = “DataScience"; // valid character array initialization
char name[12] = {‘d',‘a',‘t',‘a',‘s',‘c',‘i',’e’,’n’,’c’,’e’,'0'}; // valid initialization
char ch[3] = “data"; // Illegal
char str[4];
str = “data"; // Illegal
GO TO TOPICS

28.  strlen()
o prototype: int strlen(char *);
o It calculates the length of the given string
 strrev()
o prototype: char* strrev(char*);
o It reverses the given string
 strlwr()
o prototype: char* strlwr(char*);
o It converts the given string into its corresponding lower case
 strupr()
o prototype: char* strupr(char*);
o It converts the given string into its corresponding upper case
 strcpy()
o prototype: char* strcpy(char*, char*);
o It copies the second string into first

29.  strcat()
o prototype: char* strcat(char*, char*);
o It simply appends or concatenates the two strings.
 strcmp()
o prototype: int strcmp(char*, char*);
o It compares two strings and return -1, 0 or 1, indicative values.
Return 0 if strings are identical.
Returns -1 if first string appears before the second string in the dictionary.
Returns 1 if first string appears after the second string in the dictionary.
OR
 if Return value < 0 then it indicates str1 is less than str2.
 if Return value > 0 then it indicates str2 is less than str1.
 if Return value = 0 then it indicates str1 is equal to str2.

30. Example:1&2#include <stdio.h>
#include <string.h>
int main()
{
char str1[12] = "Hello";
char str2[12] = "Team";
char str3[12];
int len ;
/*copy str1 into str3 */
strcpy(str3, str1);
printf("strcpy(str3, str1) : %sn", str3 );
/*concatenates str1 and str2 */
strcat (str1, str2);
printf("strcat(str1, str2) : %sn", str1 );
/*total lenghth of str1 after concatenation */
len = strlen (str1);
printf("strlen(str1) : %dn", len );
return 0;
}
#include <stdio.h>
#include <string.h>
int main ()
{
char src[50], dest[50];
strcpy(src, "This is source");
strcpy(dest, "This is destination");
strcat(dest, src);
printf("Final destination string : |%s|", dest);
return(0);
}

31. Example:3
#include <stdio.h>
#include <string.h>
int main ()
{
char str1[15];
char str2[15];
int ret;
strcpy(str1, "abcdef");
strcpy(str2, "ABCDEF");
ret = strcmp(str1, str2);
if(ret < 0)
{
printf("str1 is less than str2");
}
else if(ret > 0)
{
printf("str2 is less than str1");
}
else
{
printf("str1 is equal to str2");
}
return(0);
}

32. 2.What does the following statement imply?
int arr[]={1,2,3,4,5,6,7,8,9,10};
A. Array uses only data type in its declaration
B. Array uses continuous memory addresses
C. Array is expandable
D. Array is derived data type
1. What is not true for an array?
A. The integer array does not contain any element.
B. The array contains 10 elements and the values are
natural numbers between 1 to 10.
C. The statement is not valid.
D. Array should have a dimension which is not given here.
GO TO TOPICS

33. 4. A matrix is a
A. We may use a loop to feed values into array.
B. An array can contain values belonging to different data type
categories.
C. An array can have only one dimension
D. An array cannot be copied to another variable of fundamental
data type
3. Which of the following statements is false?
A. Single dimensional array
B. Two dimensional array
C. Three dimensional array
D. Four dimensional array

34. 6. How many elements may be accommodated in
an array of dimension m and n? int arr[m][n]
A. Nested brackets are not allowed
B. There should not be any comma among between the numbers
C. There must be commas between the rows
D. The matrix is not having any dimensions mentioned for it.
5. What is wrong in this expression?
int mat[][]={{3,4},{7,8},{4,5},{20,10}}
A. Total number of elements that can be accommodated will
be m x n.
B. Total of m number of elements can be accommodated.
C. Total of n number of elements can be accommodated.
D. The declaration is defective

35. A. mat[0][0],mat[0][y],mat[x][0],mat[x][y]
B. mat[y][0],mat[0][y],mat[0][x],mat[x][y]
C. mat[0][x],mat[0][y],mat[x][0],mat[y][0]
D. mat[x][0],mat[x][y],mat[y][0],mat[y][y]
7. What are the four corner points of a matrix declared as int
mat[x][y]?

36. 9. Which function is used for checking if a
character is a control character?
A. isletter()
B. checkalpha()
C. isalpha()
D. checkletter()
8. Which function is used for checking if a character is
alphabet?
A. isspecial()
B. iscntrl()
C. isgraphic()
D. checkspl()

37. 11. Which function is used for checking if a character is a
punctuation?
A. isnum()
B. isnumber()
C. isdigit()
D. checkdigit()
10. Which function is used for checking if a character is a
digit?
A. ispunct()
B. ispnct()
C. isgraphic()
D. isdigit()

38. 13. A length of the String may be calculated with
one of the following function. Identify the same.
A. Array of Characters
B. Array of Characters terminated with a ‘0’ null character
C. Is an object
D. Same as characters
12. String ar
A. strlength()
B. strlen()
C. strln()
D. length()

39. 15. If you have to write a function for finding the length
of string. What will be the logic?
A. Joining two String
B. Merging two String
C. Cutting one string with another
D. None of the above
14. strcat() is used for
A. Read the character in an array and count them until you reach the and of the
array
B. Read the character in an array and count them until you encounter a ‘0’.
C. The dimension of the declared character is the length of the string
D. None of the Above

40. Continue……
In Slide 3