TA ZC142-L6

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TA ZC142 Computer ProgrammingLecture 6

Date: 25/01/2013

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Last Lecture

Continue loops

Do-While Loop

Arrays Derived Data Types

1-D Array

2-D Array

Memory organization

Programming Exercises

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Todays Agenda

Character Arrays (Strings)

Array of strings

Programming Exercise

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Arrays

Derived Data Type

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Arrays

An array is fixed sizesequencedcollection ofelements of the samedata typeaddressableby index or subscript.

It can be used to represent a list ofhomogenous values

Examples: List of marks of students

List of employee id no.s in an organization

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One Dimensional Arrays

List of items given one variable name using

only one subscript Declaration:

type variable_name[size];

Here size indicates the maximum number ofelements

The subscript value start from 0 to size-1

Example:

int number[10];

float number[10];

char grade[10];

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Two Dimension Array

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Two dimensional arrays also called as matrix

Declaration:

type variable_name[size1][size2];

size1>Number of rows in matrix

size2> Number of columns in matrix

Examples:

int number[4][3]; /* 12 elements */ float number[3][2]; /* 6 elements */

char name[10][20]; /* 200 chars */

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Initialization of a 2-D Array int a[2][3]={1,2,3,4,5,6};

int a[2][3]={{1,2,3}, {4,5,6}}; int a[][3]={{1,2,3}, {4,5,6}} ;

How values will be assigned in each case??

Following initializations are not allowed

int a[3][]={2,4,6,8,10,12};

int a[][]={2,4,6,8,10,12};

Note:If the first bracket pair is empty, thencompiler take the size from the number of inner

brace pairs

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Memory Map for 2-D Arrays

Kept in memory as a linear sequence of variables.

Two methods for storing- Row major

Column major

Example: int a[3][3];

Row major storage:

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][2]

Column major storage: a[0][0], a[1][0], a[2][0], a[0][1], a[1][1], a[2][1],

a[0][2], a[1][2], a[2][2]

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Accessing Two Dimensional Array

int a[3][4]={1,2,3,4,5,6,7,8,9,10,11,12}; for(i=0;i

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Working with two dimensional Arrays

Matrix Addition and Subtraction

Let A[m][n] and B[p][q] are two matrices.

Precondition: m equals to p and n equals to q

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Matrix Addition

Algorithm Steps:

1. Read two matrices A and B andinitialize C matrix to zero

2. Repeat (3) for i=0 to m-1

3. Repeat (3.a) for j=0 to n-1

3.a) C[i][j] = A[i][j] +B[i][j]

4. Display C matrix.

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Write a program to find total marks of 5

students in 3 subjects and store the totalmarks of each student in a onedimensional array. Also find the highest

marks in each subject and store in anotherarray.

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Matrix Multiplication:

M1xM2

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Pre condition: Number of columns in M1 should beequal to number of rows in M2

Algorithm Steps: 1. Read two matrices M1[m][n] and M2[n][r] and

initialize another matrix M3[m][r] for storing result.

2. Repeat fori=0 to m-13. Repeat forj=0 to r-1

4. M3[i][j] = 0

5.

Repeat fork=0 to n-16. M3[i][j] += M1[i][k] * M2[k][j]

7. 3. Print matrix M3.

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Write a program to find transpose of amatrix

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Strings

Strings in C are represented by array ofcharacters

End of the string is marked with a specialcharacter NULL.

The corresponding escape sequence characteris \0.

C does not have string data type. Declaration of strings:

char str[30];

char line[80];

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String Initialization

char str[9] = I like C;

same as char str[9]={I, ,l,i,k,e, ,C,\0};

Q. Is there any difference between followingInitialization?

char str[]=BITS;

char str[4]= BITS;

Ans: Yes, in second declaration there is no

null character

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Printing Strings

char text[]=C Programming;printf("%s\n",text);

printf("%10.5s\n",text);

printf("%-10.5s",text);

Output???

C Programming C Pro

C Pro

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Reading a

String

Using scanf()

char text[30];

printf(Enter a string: ); scanf(%s,text);

printf(The string is : %s,text);

Sample output: Enter a string: hello

The string is: hello

Enter a string: hello how are you


Note: scanf() takes str ing w ithou t blank space

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Reading a

String

char text[30]; printf(Enter a string: );

scanf(%[a-z]s,text);


Sample output:

Enter a string: hello The string is: hello

Enter a string: hello123


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Single Line input char text[80];

printf(Enter a string: );

scanf(%[^\n]s,text);/*newlineterminated string */


Sample output: Enter a string: hello how are you

The string is: hello how are you

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Multi line Input char text[180];

printf(Enter a string terminate with ~: ); scanf(%[^~]s,text);


Note: After ^ any character can be used toterminate the input.

Sample output:

Enter a string terminate with ~: hello how areyou. ~

The string is: hello how are you.

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Input String using gets()

char str[200]; printf(Enter a string :);

gets(str);

printf(The string is :%s,str);

Output

Enter a string :C programming

The string is : C programming

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int main()

{ char s[80],ws[80];

int i,j;

printf(Enter the text:\n);

gets(s);/* reading text from user */

printf(The text without blank space is:\n);

puts(ws);/* printing text on monitor */

return;

}

for(i=0,j=0; s[i]!=\0; i++)

{ if(s[i]!= )ws[j++] = s[i];

}ws[j]=\0;

Impo tant Cha acte f nctions in ct pe h

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Important Character functions in ctype.h

isdigit(c) /*Returns a nonzero if c is a digit*/

islower(c) /* Returns a nonzero if c is a lower case

alphabetic character */

isalpha(c) /*Returns a nonzero if c is an alphabet*/

isspace(c) /*Returns a nonzero for blanks */

isupper(c) /*Returns a nonzero if c is capital letter*/

toupper(c) /* Returns upper case of c */

tolower(c)/* Returns lower case of c */

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String Manipulation functions in string.h

strcpy(s1,s2)/* copies s2 into s1 */

strcat(s1,s2)/* concatenates s2 to s1 */

strlen(s)/* returns the length of s */

strcmp(s1,s2)/*returns 0 if s1 and s2 are same

returns less then 0 if s1s2 */

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String length

char txt[100],c; int i=0,len=0;

gets(txt);

while(txt[i] != '\0') {

i++;

} printf("len = %d\n",i);

printf("len using strlen is %d\n",strlen(txt));

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Implementation of strcat() void main()/* s2 is concatenated after s1 */

{

char s1[100],s2[100];

int i = 0,j = 0;

printf("Enter first string\n");

scanf("%[^\n]",s1);

printf("Enter second string\n");

scanf("%[^\n]",s2);

while(s1[i++] != '\0');

i--;

while(s2[j] != '\0')

s1[i++] = s2[j++];

s1[i] = '\0';

printf("\n Final string is:%s",s1);

}

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Palindrome problem: Implementation

void main()

{ char str[80];int left,right,i,len,flag = 1;printf ("Enter a string");for(i = 0;(str[i] = getchar())!='\n';++i);len = i-1;for(left = 0,right = len; left < right; ++left,--right){ if(str[left]!= str[right])

{ flag = 0;break;

}}if(flag)printf("\n String is palindrome");else

printf("\n String is not a palindrome");}

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Write a program to read a matrix ofcharacters. Dimensions are taken from

the user.

(a) Convert a lower case alphabet intoupper case alphabet.

if there is a character other thanalphabet replace that character with

$. Display the final matrix with all the

upper case alphabets and $.

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(b) Find the vowels inthe resultant

matrix. Printnumber of vowelsin each row. Alsoprint the vowel

along with its index.

a f # T @

i s ! o m

V 5 u Q i

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Array of Strings

Exercise on Array of Strings

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Arrays of Strings

Declaration:

char name[5][30];

Five strings each contains maximum thirty characters.

Initialization: char[5][10]={One,Two,Three,Four,Five};

Other valid declarations:

char[][]={One,Two,Three,Four,Five};

char[5][]={One,Two,Three,Four,Five};

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String Arrays: Reading and Displaying

void main()

{ char name[5][30];

printf(\n Enter five strings);

/* Reading strings */

for(i=0;i

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Programming on Array of

String

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Write a C program to read the full name ofthe customers and their telephone numbers.

Full name includes Surname followed by firstname and then the middle name.

Sort the customer names in alphabetical

order with surname first followed by comma(,) and initials of the first and middle names.Display this sorted customer list along with

their telephone no. E.g Ghokle Suraj Ram should be written as

Ghokle,S.R

OUTPUT

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OUTPUT

asma@atlas:~/cp1$ ./a.out

Enter names and telephone numberssharma anil sudhir 1234

verma mona abhay 9876

garg sona abhi 7654

modak tinu pintu 9870shree shits sumit 8765

Customer list in alphabetical order

garg,s.a 7654modak,t.p 9870

sharma,a.s 1234

shree,s.s 8765

verma,m.a 9876

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Declarations

charfname[20][10],mname[20][10],sname[20][10];

charname[20][15],telephone[20][10],dummy[20];

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for(i=0;i

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Code for Sorting list in alphabetical order along

with telephone numbers

for(i=1;i

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Print the list

for(i=0;i

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Exercise : Array of Strings

Problem Statement: Write a C program thatwill read and store the details of a list ofstudents in the format

ID NAME MARKS

And produce the following output

1. Alphabetical list of Names, IDs and Marks.

2. List sorted on IDs3. List sorted on Marks

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Exercise

1. Write a C program which will read aline of text and rewrite it in the

alphabetical order.

2. Write a C program to replace a

particular word by another word in agiven string. Both the words areprovided by the user at run time.

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Any Doubts orQuestions?

Documents

TA ZC142-L6