UNIT III ARRAYS AND STRINGS

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1 UNIT III ARRAYS AND STRINGS Arrays Initialization Declaration One dimensional and Two dimensional arrays. String- String operations String Arrays. Simple programs- sorting- searching matrix operations. ARRAYS Definition : Array is a collection of same data type elements under the same variable name referenced by index number. Arrays allow you to store group of data of a single type. Characteristics: Ex: An array is a derived data type. It is used to represent a collection of elements of the same data type. The elements can be access with base address (index) and the subscripts define the position of the element. In array the elements are stored in continuous memory location, the starting memory location is represented by the base address of the array It is easier to refer the array elements by simply incrementing the value of the subscript Array is a linear and homogeneous data structure int a[5]; It tells the compiler that a is an integer type of array and can store 5 integers. Advantages: An array is a derived data type. It is used to represent a collection of elements of the same data type. The elements can be access with base address (index) and the subscripts define the position of the element. In array the elements are stored in continuous memory location, the starting memory location is represented by the base address of the array It is easier to refer the array elements by simply incrementing the value of the subscript GE 6151 Unit III 1

2 Rules of Array: It does not check the boundary. Processing time will increase when working with large data because of increased memory. The array element start with zero not 1. Character array size must be one element greater than data for NULL value. One variable for control structure is required to assign and read value to one dimensional array. Two variable for control structures are required to assign and read value to two dimensional arrays. No two arrays can have the same name but arrays and ordinary variable can be assigned the same name. Classification of arrays: One dimensional Array Two Dimensional Array Multi-Dimensional Array One Dimensional Array: A list of items can be given one variable name using only one subscript and a variable is called one dimensional array or single subscripted variable. Declaration: Arrays are declared in the same manner as an ordinary variables except that array name must have the size of an array Description: Data type-> specifies the type of the data Array name -> specify the name of the array Data_type Array_name[size]; Size -> specify the maximum number of elements that the array can hold Ex: int a[5]; //Here a is integer array with 5 subscript a[0] a[1] a[2] GE 6151 Unit III 2

3 a[3] a[4] Initializing an array: The values can be initialized to an array when they are declared like ordinary variables otherwise they hold garbage values. The array can be initialized in the following two types: o At compile time(static Initialization) o At run time(dynamic Initialization) static Initialization: Data_type Array_name[size] = list of values The list of values must be separated by commas. Ex: Int marks[5]= 70,80,98,35,56; marks[0] marks[1] marks[2] marks[3] marks[4] int age[]=2,4,34,3,4; The elements can be used like ordinary variables Character array can also initialized in similar manner Ex: char name[10]= R, A, J ; The above statements declare the name variables as an array of character with the string LAK. Dynamic Initialization: The array can be explicitly initialized at run time. GE 6151 Unit III 3

4 Ex: int sum[5]; for(int i=0;i<5;i++) sum[i]=i; Like the array can also be initialized by reading data from the user. Ex: int sum[5]; for(int i=0;i<5;i++) scanf( %d,&a[i]); Accessing Array Elements: In C programming, arrays can be accessed and treated like variables in C. #include <stdio.h> void main() int marks[10],i, n, sum=0; printf("enter number of students: "); scanf("%d",&n); for(i=0;i<n;++i) printf("enter marks of student%d: ",i+1); scanf("%d",&marks[i]); sum+=marks[i]; printf("sum= %d",sum); Enter number of students: 3 Enter marks of student1: 12 Enter marks of student2: 31 Enter marks of student3: 2 sum=45 Program to accept 5 numbers and print whether the number is even or odd. #include <stdio.h> #include<conio.h> GE 6151 Unit III 4

5 void main() int array[5], I; clrscr(); printf("enter the elements of the array \n"); for (i = 0; i <5; i++) scanf("%d", &array[i]); printf("even numbers in the array are - "); for (i = 0; i < 5; i++) if (array[i] % 2 == 0) printf("%d \t", array[i]); printf("\n Odd numbers in the array are -"); for (i = 0; i <5; i++) if (array[i] % 2!= 0) printf("%d \t", array[i]); getch(); Two dimensional array: Two dimensional arrays are used in situation where a table of values need to be stored in an array. These can be defined in the same manner as in one dimensional array except a separate pair of square brackets are required for each subscript Data_type Array_name[row_size][column_size]; Two dimensional arrays are stored in a row column matrix where the left index indicated the row and the right index indicated the column. GE 6151 Unit III 5

6 Void main() int a[3][3]=1,2,3,4,5,6,7,8,9; clrscr(); printf( Array Elements and Address\n ); for (i=0;i<3;i++) for(j=0;j<3;j++) printf( %d[%d]\t,a[i][j],&a[i][j]); printf( \n ); 1[2000] 2[2002] 3[2004] 4[2006] 5[2006] 6[2007] 7[2009] 8[2011] 9[2013] Transpose of Matrix #include<stdio.h> #include<conio.h> void main() int r,c,i,j,m[10][10]; clrscr(); printf("enter number of rows and columns:"); scanf("%d %d",&r,&c); for(i=0;i<r;i++) for(j=0;j<c;j++) scanf("%d",&m[i][j]); printf("\nthe Transpose matrix"); for(i=0;i<r;i++) printf("\n"); for(j=0;j<c;j++) printf(" %d",m[j][i]); getch(); GE 6151 Unit III 6

7 Matrix Addition: #include <stdio.h> #include<conio.h> void main() int m, n, c, d, first[10][10], second[10][10], sum[10][10]; clrscr(); printf("enter the number of rows and columns of matrix\n"); scanf("%d%d", &m, &n); printf("enter the elements of first matrix\n"); for (c = 0; c < m; c++) for (d = 0; d < n; d++) scanf("%d", &first[c][d]); printf("enter the elements of second matrix\n"); for (c = 0; c < m; c++) for (d = 0 ; d < n; d++) scanf("%d", &second[c][d]); printf("sum of entered matrices:-\n"); for (c = 0; c < m; c++) for (d = 0 ; d < n; d++) sum[c][d] = first[c][d] + second[c][d]; printf("%d\t", sum[c][d]); printf("\n"); getch(); Matrix Multiplication: #include <stdio.h> #include<conio.h> void main() int m, n, p, q, c, d, k, sum = 0; int first[10][10], second[10][10], multiply[10][10]; clrscr(); printf("enter the number of rows and columns of first matrix\n"); scanf("%d%d", &m, &n); printf("enter the elements of first matrix\n"); GE 6151 Unit III 7

8 for (c = 0; c < m; c++) for (d = 0; d < n; d++) scanf("%d", &first[c][d]); printf("enter the number of rows and columns of second matrix\n"); scanf("%d%d", &p, &q); if (n!= p) printf("matrices with entered orders can't be multiplied with each other.\n"); else printf("enter the elements of second matrix\n"); for (c = 0; c < p; c++) for (d = 0; d < q; d++) scanf("%d", &second[c][d]); for (c = 0; c < m; c++) for (d = 0; d < q; d++) for (k = 0; k < p; k++) sum = sum + first[c][k]*second[k][d]; multiply[c][d] = sum; sum = 0; printf("product of entered matrices:-\n"); for (c = 0; c < m; c++) for (d = 0; d < q; d++) printf("%d\t", multiply[c][d]); printf("\n"); getch(); MULTI DIMENSIONAL ARRAY: An Array with more than two subscripts are called Multi Dimensional Array. GE 6151 Unit III 8

9 data_type Array_name[size1][size2][size3].[sizen]; int a[3][3][4]; float b[4][5][6][8]; Arrays with more than three subscripts are not used often Multi dimensional arrays are slower than single dimensional array. void main() int a[3][3][3],i,j,k; clrscr(); printf( Enter Array Elements:\n ); for (i=0;i<3;i++) for(j=0;j<3;j++) for(k=0;k<3;k++) scanf( %d, &a[i][j][k]); printf( Array Elements are\n ); for (i=0;i<3;i++) printf( \n ); for(j=0;j<3;j++) printf( \n ); for(k=0;k<3;k++) printf( %d\t, &a[i][j][k]); getch(); GE 6151 Unit III 9

10 SORTING Bubble Sort: #include<stdio.h> #include<conio.h> void main( ) int i,j,n,a[20],temp; clrscr( ); printf( Sorting the elements using bubble sort\n ); printf( Enter the size of the array \n ); scanf( %d,&n); printf( Enter the elements of the array:\n ); for(i=0;i<n;i++) scanf( %d,&a[i]); for(i=0;i<n;i++) for(j=0;j<n-1-i;j++) if(a[j]>a[j+1]) temp=a[j]; a[j]=a[j+1]; a[j+1]=temp; printf( The elements sorted using bubble sort are:\n ); for(i=0;i<n;i++) printf( %d\t,a[i]); getch( ); GE 6151 Unit III 10

11 SEARCHING Linear Search: #include <stdio.h> #include<conio.h> void main() int array[100], search, c, n; clrscr(); printf("enter the number of elements in array\n"); scanf("%d",&n); printf("enter %d integer(s)\n", n); for (c = 0; c < n; c++) scanf("%d", &array[c]); printf("enter the number to search\n"); scanf("%d", &search); for (c = 0; c < n; c++) if (array[c] == search) printf("%d is present at location %d.\n", search, c+1); break; if (c == n) printf("%d is not present in array.\n", search); getch(); Binary Search: #include <stdio.h> #include<conio.h> int main() int i, first, last, middle, n, search, array[100]; printf("enter number of elements\n"); scanf("%d",&n); printf("enter %d integers\n", n); for ( i = 0 ; i < n ; i++ ) scanf("%d",&array[i]); printf("enter value to find\n"); GE 6151 Unit III 11

12 scanf("%d",&search); first = 0; last = n - 1; middle = (first+last)/2; while( first <= last ) if ( array[middle] < search ) first = middle + 1; else if ( array[middle] >search ) last=middle+1; else printf("%d found at location %d.\n", search, middle+1); if ( first > last ) printf("not found! %d is not present in the list.\n", search); return 0; String is the collection of characters. STRING In c language, the group of characters, digits and symbols enclosed with in is called string A string is declared as a one dimensional array of characters. The string is terminated by a null( \0 ) character It is not compulsory to add \0 in a string, compiler will automatically puts \0 in a string The string are normally used to manipulate the text such as words and sentences. Header file used is string.h String Declaration: Ex: Datatype variable_name [size]; char name[30]; String Initialization: Ex: Datatype variable_name [size] = string; char name[]= r, a, j, a, \0 ; GE 6151 Unit III 12

13 where the \0 is specified at the end of string C provides another method for initialing string char name[]= raja ; Here \0 is not necessary Reading & writing String: The %s control string can be used in scanf() function to read a string from the terminal. and same may be used to write string to the terminal in printf() function. Ex: char a[10]; scanf( %s, a); printf( %s, a); Built-in String functions/ String Operations/ String Manipulation Functions: There are several string functions to work with string variables and its values. These functions are available C header file called string.h. Consider the following example: char string1[15]= Hello ; char string2[15]= World ; 1) Copying String strcpy(destination,source); Here, source and destination are both the name of the string. This statement, copies the content of string source to the content of string destination. This function will replace the existing value of destination with source. char string1[15]= Hello ; char string2[15]= World ; strcpy(string1,string2); printf( %s%s,string1,string2); output: World World 2) Comparing String: Case Sensitive: This function compares the value from string2 with string1. If both the string1 and string2 are exactly the same then the function will return zero or else it will return some positive or negative value. For the above example the function will return negative of positive value. Here string1 and string2 will not change. GE 6151 Unit III 13

14 strcmp(string1,string2); int n; char string1[15]= Hello ; char string2[15]= Hello ; n=strcmp(string1,string2); printf( %n,n); 0 Non-Case Sensitive: stricmp(string1, string2); int n; char string1[15]= Hello ; char string2[15]= hello ; n=stricmp(string1,string2); printf( %n,n); 0 3) Concatenation String strcat(string1,string2); This function is used to join two strings. It concatenates source string at the end of destination string. Here String 2 is concatenate with String1. char string1[15]= Hello ; char string2[15]= World ; n=strcat(string1,string2); printf( %s,string1); HelloWorld strncat(string1,string2,no_of_characters); This function is used to join two strings. It concatenates portion of source string at the end of destination string. Here String 2 is concatenate with String1. char string1[15]= Hello ; char string2[15]= World ; GE 6151 Unit III 14

15 n=strcat(string1,string2,3); printf( %s,string1); HelloWor 4) Copying String strcpy(string1,string2); This function copy s the contents of one string2 into another string1. char string1[15]= Hello ; char string2[15]= World ; n=strcpy(string1,string2); printf( %s,str1); World strncpy(string1,string2,no_of_characters); This function copies portion of contents of one string2 into another string1. char string1[15]= ; char string2[15]= Hello World ; n=strcpy(string1,string2,5); printf( %s,string1); Hello 5) Find a value in string (strstr()) This function will find the first occurance of string2 in string1. Assume string1 as Apple and string2 as Ap, now the function will return first occurrence of Ap, since Ap is found in Apple. o strstr(string1, string2); char string1[20] = "Hello "; char string2[10] = "World"; printf("the substring is: %s\n", strstr(string1,string2)); World 6) Find a value in string (strrstr()) This function will find the last occurance of string2 in string1. GE 6151 Unit III 15

16 Assume string1 as Apple and string2 as Ap, now the function will return position of first occurrence of Ap, since Ap is found in Apple. o strrstr(string1, string2); char string1[20] = "Hello world "; char string2[10] = "World"; printf("the substring is: %s\n", strrstr(string1,string2)); o World 7) Find a character in string (strchr()) strchr( ) function returns pointer to the first occurrence of the character in a given string strchr(string,chracter); char string1[15]= Hello World ; printf(strchr(string1, l )); 3 8) Duplicate String: strdup( ) function in C duplicates the given string string2=strdup(string1); char string1= Hello ; char string2; string2=strdup(string1); printf( %s,string2); Hello 9) Find a character in string (strrchr()) strchr( ) function returns pointer to the last occurrence of the character in a given string strrchr(string,chracter); char string1[15]= Hello World ; printf(strrchr(string1, l )); GE 6151 Unit III 16

17 10 10) Reversing a string strrev( ) function reverses a given string in C language strrev(string1); char name[30] = "Hello"; printf("string after strrev( ) : %s",strrev(name)); String after strrev( ) : olleh 11) Length of String This function will return length of the string. strlen(string1); int len; char array[20]="hello " ; len = strlen(array) ; printf ( "string length = %d ", len ) ; String Length = 5 12) Convert Lower case to Uppercase strupr( ) function converts a given string into uppercase strlwr(string1); char str[ ] = "Modify This String To Upper"; printf("%s\n",strupr(str)); MODIFY THIS STRING TO UPPER 13) Convert Uppercase to Lower case strlwr( ) function converts a given string into lower case strupr(string1); char str[ ] = " MODIFY This String To LOwer"; printf("%s\n",strlwr(str)); GE 6151 Unit III 17

18 modify this string to lower 14) Set character: sets all character in a string to given character strset(string1,character); char str[ ] = " Hello"; printf("%s\n",strset(str, # )); ##### 15) Set character: sets portion of characters in a string to given character. strnset(string1,character,number); char str[ ] = " Hello"; printf("%s\n",strnset(str, #,4)); ####0w Palindrome of string data #include <stdio.h> #include <conio.h> #include <string.h> int r; char s1[15], s2[15]; void main() clrscr(); printf("enter a string :"); scanf("%s", s1); strcpy(s2,s1); //copy's s1 to another variable s2 strrev(s2); //reverse the value of s2 printf("%s\n", s1); printf("%s\n", s2); r= strcmp(s1,s2); if (r==0) printf("it is a Palindrome %s\n", s1); else printf("it is not a Palindrome %s\n", s1); GE 6151 Unit III 18

19 getch(); Simple Programs: Binary Search #include <stdio.h> void main() int c, first, last, middle, n, search, array[100]; printf("enter number of elements\n"); scanf("%d",&n); printf("enter %d integers\n", n); for (c = 0; c < n; c++) scanf("%d",&array[c]); printf("enter value to find\n"); scanf("%d", &search); first = 0; last = n - 1; middle = (first+last)/2; while (first <= last) if (array[middle] < search) first = middle + 1; else if (array[middle] == search) printf("%d found at location %d.\n", search, middle+1); break; else last = middle - 1; middle = (first + last)/2; if (first > last) printf("not found! %d is not present in the list.\n", search); Insertion Sort: #include <stdio.h> void main() GE 6151 Unit III 19

20 int n, array[1000], c, d, t; printf("enter number of elements\n"); scanf("%d", &n); printf("enter %d integers\n", n); for (c = 0; c < n; c++) scanf("%d", &array[c]); for (c = 1 ; c <= n - 1; c++) d = c; while ( d > 0 && array[d] < array[d-1]) t = array[d]; array[d] = array[d-1]; array[d-1] = t; d--; printf("sorted list in ascending order:\n"); for (c = 0; c <= n - 1; c++) printf("%d\n", array[c]); Selection Sort: #include <stdio.h> void main() int array[100], n, c, d, position, swap; printf("enter number of elements\n"); scanf("%d", &n); printf("enter %d integers\n", n); for ( c = 0 ; c < n ; c++ ) scanf("%d", &array[c]); for ( c = 0 ; c < ( n - 1 ) ; c++ ) position = c; GE 6151 Unit III 20

21 for ( d = c + 1 ; d < n ; d++ ) if ( array[position] > array[d] ) position = d; if ( position!= c ) swap = array[c]; array[c] = array[position]; array[position] = swap; printf("sorted list in ascending order:\n"); for ( c = 0 ; c < n ; c++ ) printf("%d\n", array[c]); Quick Sort: #include<stdio.h> void quicksort(int [10],int,int); void main() int x[20],size,i; printf("enter size of the array: "); scanf("%d",&size); printf("enter %d elements: ",size); for(i=0;i<size;i++) scanf("%d",&x[i]); quicksort(x,0,size-1); printf("sorted elements: "); for(i=0;i<size;i++) printf(" %d",x[i]); void quicksort(int x[10],int first,int last) int pivot,j,temp,i; GE 6151 Unit III 21

22 if(first<last) pivot=first; i=first; j=last; while(i<j) while(x[i]<=x[pivot]&&i<last) i++; while(x[j]>x[pivot]) j--; if(i<j) temp=x[i]; x[i]=x[j]; x[j]=temp; temp=x[pivot]; x[pivot]=x[j]; x[j]=temp; quicksort(x,first,j-1); quicksort(x,j+1,last); GE 6151 Unit III 22

Unit 1 - Arrays. 1 What is an array? Explain with Example. What are the advantages of using an array?

Unit 1 - Arrays. 1 What is an array? Explain with Example. What are the advantages of using an array? 1 What is an array? Explain with Example. What are the advantages of using an array? An array is a fixed-size sequenced collection of elements of the same data type. An array is derived data type. The