numeric header in C++ STL | Set 1
adjacent_difference
This functions assigns the difference between the corresponding elements of an array to another array. It returns the adjacent difference of all the set of values lying between [ First, last ).
For Example: If a[] represents an element in provided range [first, last) and b[] represents the result.
b[0] = a[1] b[1] = a[1] – a[0] b[2] = a[2] – a[1] b[3] = a[3] – a[2] b[4] = a[4] – a[3] ... ... ...
Syntax:
adjacent_difference(first, last, b); adjacent_difference(first, last, b, myfun ); adjacent_difference(first, last, b, multiplies() ) ; first, last : address of first and last element of range whose elements are to be added b:index of array where corresponding partial sum will be stored; myfun : a user defined function for performing any specific task multiplies():a pre defined function.
#include <iostream> #include <functional> // for multiplies function #include <numeric> //for adjacent_difference using namespace std; int myfun ( int x, int y) { return x+y; } int main () { int a[] = { 1, 2, 3, 4, 5, 6} ; int b[6]; // using adjacent_difference function adjacent_difference (a, a+6, b); cout << "\nResult using adjacent_difference: " ; for ( int i=0; i<6; i++) std::cout << b[i] << ' ' ; // using adjacent_difference function // user defined function adjacent_difference (a, a+6, b, myfun); cout << "\nResult using accumulate with user-" "defined function: " ; for ( int i=0; i<6; i++) std::cout << b[i] << ' ' ; // using adjacent_difference with pre-defined function adjacent_difference (a, a+6, b, multiplies< int >() ) ; cout << "\nResult using accumulate with pre-defined function: " ; for ( int i=0; i<6; i++) std::cout << b[i] << ' ' ; return 0; } |
Output:
Result using adjacent_difference: 1 1 1 1 1 1 Result using accumulate with user-defined function: 1 3 5 7 9 11 Result using accumulate with pre-defined function: 1 2 6 12 20 30
inner_product
This function returns the result of addition of var with the inner products of the pairs formed by the elements of two ranges starting at first1 and first2.
Syntax:
inner_product(first, last, b, var) ; inner_product(a, a+3, b, var, fun, fun1) ; inner_product(a , a+3, b, init, minus (), divides () ); first, last : address of first and last element of range whose elements are to be added b: index of array where corresponding partial sum will be stored; fun, fun1: a user defined function for performing any specific task minus(), divides() : pre defined function.
#include <iostream> #include <functional> // for subtraction, std::divides #include <numeric> // for inner_product using namespace std; int fun ( int x, int y) { return x-y; } int fun1 ( int x, int y) { return x+y; } int main () { int var = 200; int a[] = { 10, 15, 20} ; int b[] = { 1, 3, 5} ; cout << "\nResult using inner_product " ; // inner_product with default method cout << inner_product(a, a+3, b, var ) ; // inner_product with pre-defined function cout << "\nResult using inner_product with pre-defined function: " ; cout << inner_product(a, a+3, b, var, minus< int >(), divides< int >()); // inner_product with user defined function cout << "\nResult using inner_product with user-defined function: " ; cout << inner_product(a, a+3, b, var, fun, fun1); return 0; } |
Output:
Result using inner_product 355 Result using inner_product with pre-defined function: 181 Result using inner_product with user-defined function: 146
iota
This function assigns a value to the elements in the range [first,last ) of the array which is incremented at each step by val++ .
Syntax –
iota(first, last,val) ; first, last : address of first and last element of range whose elements are to be added val: initial value to store, the expression ++value must be well-formed
#include <iostream> #include <iostream> #include <numeric> // std::iota using namespace std; int main ( ) { int a[7]; //using iota function to store 100, 101, 102,... iota(a, a+7,100); cout << " a : " ; for ( int & x: a) cout << ' ' << x; return 0; } |
Output :
a: 100 101 102 103 104 105 106
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