Arrays

WHAT IS AN ARRAY An array is a derived data type ( derived from fundamental data type ) It is a collection of variables of the same type that are referenced by a common name. Consist of contiguous memory locations. Lowest address corresponds to first element Highest address corresponds to the last element. Can have data items of type like: int, char, float and also user-defined types like : structures, objects.

NEED FOR AN ARRAY To store large number of variables of same type under a single variable. Easy understanding of the program. E.g. To store Marks of 50 students. Record of sales of 100 salesman.

TYPES OF ARRAYS Single Dimensional Array: Element specified by single subscript Syntax: type array_name [ size ] Base type of array Name of array No. of elements that can be stored: Can be a integer value without the sign

Creating an Array void main( ) { int a[10]; // declaration of an array ‘a’ int n; // input 10 elements in an array for ( n = 0; n < 10 ; n + +) { cin >> a [ n ]; } // display the 10 elements of the array input for ( n = 0 ; n < 10 ; n + + ) { cout << a [ n ] << endl; } }

Memory Representation of Single Dimension Array If the array is float arr [ 5 ]; memory representation would be as follows: Arr [ 0 ] Arr [ 1 ] Arr [ 2 ] Arr [ 3 ] Arr [ 4 ] 5016 5012 5008 5004 5000 Total Memory requirement is : size of ( type ) * size of array 4 * 5 = 20 bytes

ARRAY INITIALISATION int list [ 5 ] ; // declaration int list [ 5 ] = { 10, 20, 30, 40, 50 } ; // declaration & initialization

UNSIZED ARRAY INITIALISATION Can skip the size of an array in array initialization Elements of an array can be added or removed without changing array dimensions. E.g. float price [ ] = { 50.5, 63.97, 84.6, 779.8 };

Program to count the no. of employees earning more than Rs. 1 lakh per annum. Monthly salaries of 10 employees are given. void main ( ) { const int size = 10 ; float sal [ size ] , an_sal ; int count = 0; // loop to accept monthly salaries of 10 employees for ( int j = 0 ; j < size ; j + + ) { cout << “ Enter the monthly salary of employee “ << j + 1 ; cin >> sal [ j ]; }

// loop to count employees earning more than Rs. 1 lakh per annum for ( j = 0 ; j < size ; j + + ) { an_sal = sal [ j ] * 12 ; if ( an_sal > 100000 ) { count ++ ; } } cout << count << “ employees out of “ << size << “ employees are earning more than Rs. 1 lakh per annum “ ; }

WAP to input 10 numbers in an array and replace all even no.s by 0 and odd no.s by 1 void main ( ) { int a [ 10 ], n; // loop to accept 10 values in an array ‘a’ for ( n = 0; n < 10 ; n + +) { cin >> a [ n ]; } // loop to check if the element of an array is even replace by 0 // and if odd replace by 1 for ( n = 0; n < 10 ; n + +) { if ( ( a [ n ] % 2 ) == 0 ) { a [ n ] = 0; } else { a [ n ] = 1 ; } } }

// display the 10 elements of the array for ( i = 0 ; i < 10 ; i + + ) { cout << a [ i ] << endl; }

WAP to find the largest and smallest no. in an array of 10 elements // input an array // display the array // to find the largest element int largest = a [ 0 ] ; for ( int i = 1 ; i < 10 ; i + + ) { if ( a [ i ] > largest ) { largest = a [ i ]; } } cout << “ largest value is : “ << largest ;

WAP to find the largest and smallest no. in an array of 10 elements // input an array // display the array // to find the lowest element int lowest = a [ 0 ]; for ( n = 1 ; n < 10 ; n + + ) { if ( a [ n ] < lowest ) { lowest = a [ n ]; } } cout << “ lowest value is : “ << lowest ;

Arrays

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Arrays