C++ STL中的数字标头|套装1
neighbor_difference
此函数将一个数组的相应元素之间的差异分配给另一个数组。它返回[First,last)之间的所有值集的相邻差。
例如:如果a []表示提供的范围[first,last)中的元素,而b []表示结果。
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]
... ... ...
句法:
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
#include // for multiplies function
#include //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() ) ;
cout << "\nResult using accumulate with pre-defined function: " ;
for (int i=0; i<6; i++)
std::cout << b[i] << ' ';
return 0;
}
输出:
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
内部产品
此函数返回将var与从first1和first2开始的两个范围的元素形成的对的内积相加的结果。
句法:
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
#include // for subtraction, std::divides
#include // 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(), divides());
// 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;
}
输出:
Result using inner_product 355
Result using inner_product with pre-defined function: 181
Result using inner_product with user-defined function: 146
iota
该函数为数组[first,last)范围内的元素分配一个值,该值在每个步骤中以val ++递增。
句法 –
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
#include
#include // 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;
}
输出 :
a: 100 101 102 103 104 105 106
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