introduction to Array and Function in c++.pptx

introduction to Array and Function in c++.pptx

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  Lecture 2 Function andArray Faculty of Computer Science Jamilurahman Faizi Structure programming
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  FUNCTION AND ARRAY Generallywe pass values and variable while calling a function, likewise we can also pass arrays to a function as argument you can pass arrays element as well as whole array by just (specifying the array name) which works as a pointer to a function. We can pass array element • Each element one by one • Entire array 09/06/2025 NU-CSF 3
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  EXAMPLE #include<stdio.h> #include<conio.h> disp( char ch) { cout<<ch; } intmain() { int x; char arr[]={'a','b','c','d','e','f','g','h','i','j'}; for( x=0;x<10;x++) { disp(arr[x]); } return 0; } 09/06/2025 NU-CSF 4
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  EXAMPLE • Write aprogram that input five integers in array and passes the array to a function and then display its value? 09/06/2025 NU-CSF 5
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  #include<iostream> using namespace std; voidfshow(int arr[]); int main() { int num[5],a; cout<<"enter 5 int values"; for( a=0;a<5;a++) cin>>num[a]; fshow(num); return 0; } void fshow(int arr[]) { int d; cout<<"the values in array are n"; for(d=0;d<5;d++) cout<<" n"<<arr[d]; } 09/06/2025 NU-CSF 6
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  EXAMPLE • Write aprogram that inputs five integers in array and passes array to a function the function counts even numbers in array and returns result to calling function. 09/06/2025 NU-CSF 7
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  #include<iostream> using namespace std; inteven(int arr[]); int main() { int num[5],i,n,a; cout<<"enter 5 int values"; for( a=0;a<5;a++) cin>>num[a]; n=even(num); cout<<"the array contains "<<n<<" even numbers"; } int even(int arr[]) { int e=0,i; for( i=0;i<5;i++) if(arr[i]%2==0) e++; return e; } 09/06/2025 NU-CSF 8
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  PASSING 2DIMENSIONAL ARRAYTO FUNCTION Write a program that inputs value in a 2-d array with 3 rows and 2 columns the program passes the array to function and the function return the maximum value? 09/06/2025 NU-CSF 9
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  #include<iostream> using namespace std; intmax(int arr[3][2]); main() { int num[3][2],mx,a,b; cout<<"enter 6 integer values"; for( a=0;a<3;a++) for( b=0;b<2;b++) cin>>num[a][b]; mx=max(num); cout<<"the max value ="<<mx; } int max(int arr[3][2]) { int m=0,s,d; for( s=0;s<3;s++) for( d=0;d<2;d++) if(arr[s][d]>m) m=arr[s][d]; return m; } 09/06/2025 NU-CSF 10
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  SEARCHING IN ARRAY •Searching is the process of finding the required data in the array . searching becomes more important when the length of an array is very large. There are two types of search • Sequential search • Binary search
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  SEQUENTIAL SEARCHING • Sequentialsearch is also called linear search or serial search which is a simple way to search an array for the desired value. Loops are frequently used to visit elements of array for searching a value. • As the name implies it searches the array starting with the first array component it compares the search item with the elements in the array starting at position zero and continues the search until it finds the item or until no more data is left in the list to be compared with the searched items. 09/06/2025 NU-CSF 12
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  ADVANTAGE o Simplicity. o Itis easy to understand o Easy to implement o Does not require the array to be in order o The disadvantage is its inefficiency o If there are 20,000 items in the array and what you are looking for is in the 19,999th element, you need to search through the entire list. 09/06/2025 NU-CSF 13
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  EXAMPLE • Write downa program that initializes an array that input a value from the user and search a number in array. 09/06/2025 NU-CSF 14
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  #include<iostream> using namespace std; main() { intarr[]={1,2,3,4,5,6,7,8,9}; int i,n,loc=-1; cout<<"enter value to find"; cin>>n; for(i=0;i<=8;i++) if(arr[i]==n) loc=i; if(loc!=-1) cout<<"value found at positon="<<loc; else cout<<"value does not exist"; } 09/06/2025 NU-CSF 15
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  EXAMPLE #include<iostream> using namespace std; intarrsize=5; int seqsearch(int list[], int listlength, int searchitem); main() { int intlist[arrsize]; int number, index; cout<<"enter "<<arrsize<<" integers value"; for(index=0;index<arrsize;index++) cin>>intlist[index]; cout<<"enter no to find"; cin>>number; index=seqsearch(intlist,arrsize,number); if(index!=-1) cout<<"no found at position "<<index; else cout<<"no not found"; return 0; } 09/06/2025 NU-CSF 16
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  CONT… int seqsearch(int list[],intlistlength,int searchitem) { int l,res; for(l=0;l<listlength;l++) { if(list[l]== searchitem) return l; else res= -1; } return res; } 09/06/2025 NU-CSF 17
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  BINARY SEARCH • Binarysearch is much more efficient than linear search. • It requires the list to be in order. • The algorithm starts searching with the middle element. • If the item is less than the middle element, it starts over searching the first half of the list. • If the item is greater than the middle element, the search starts over starting with the middle element in the second half of the list. • It then continues halving the list until the item is found.
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  EXAMPLE Write a programthat initializes an array of size 12, it inputs an integer from the users and searches the value in the array using binary search.
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  BINARY SEARCH #include<iostream> using namespacestd; int main() { int arr[12]={4,20,30,40,50,60,70,80,90,99,100,110}; int n,i,mid,start,end,loc; loc=-1; start=0; end=11; cout<<"enter any number to find"; cin>>n; while(start<=end) { mid=(start+end)/2; if(arr[mid]==n) { loc=mid; break; } else if(n<arr[mid]) end=mid-1; else start=mid+1; } if(loc==-1) cout<<"the value not found"; else cout<<n<<" vlaue found at index="<<loc; return 0; }
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  REFERENCE BOOKS • Bjarnestroustrup. (2017). Programming principles and practice using c++. 6th edition. • Paul deitel and harvey deitel "c++ how to program" • Malik, d. S. (2014). C++ programming: from problem analysis to program design. Cengage learning.