cb39a_c++_STL_算法_for_each_transform_比较
for_each() 速度快，不灵活
transform() 速度慢， 非常灵活
STL算法-修改性算法
for_each()
copy()
copy_backward()
transform()
merge()
swap_ranges()
fill()
fill_n()
generate()
generate_n()
replace()
replace_if()
replace_copy()
replace_copy_if()
void square(int &elem)//for_each参数必须是按引用传递，速度快
{
elem = elem*elem;
}
int square2(int elem)//transform不能传引用，传copy，速度慢
{
return elem * elem;
}
int main()
transform(b.begin(), b.end(), b.begin(), square2);
1 /*cb39a_c++_STL_算法_for_each_transform_比较 2 for_each() 速度快，不灵活 3 transform() 速度慢， 非常灵活 4 5 STL算法-修改性算法 6 for_each() 7 copy() 8 copy_backward() 9 transform() 10 merge() 11 swap_ranges() 12 fill() 13 fill_n() 14 15 generate() 16 generate_n() 17 replace() 18 replace_if() 19 replace_copy() 20 replace_copy_if() 21 22 void square(int &elem)//for_each参数必须是按引用传递，速度快 23 { 24 elem = elem*elem; 25 26 } 27 int square2(int elem)//transform不能传引用，传copy，速度慢 28 { 29 return elem * elem; 30 } 31 32 int main() 33 transform(b.begin(), b.end(), b.begin(), square2); 34 */ 35 36 #include <iostream> 37 #include <algorithm> 38 #include <vector> 39 40 using namespace std; 41 void square(int &elem)//for_each参数必须是按引用传递，速度快 42 { 43 elem = elem*elem; 44 45 } 46 int square2(int elem)//transform不能传引用，传copy，速度慢 47 { 48 return elem * elem; 49 } 50 51 int main() 52 { 53 vector<int> a; 54 vector<int> b; 55 for (int i = 1; i <= 9; ++i) 56 { 57 a.push_back(i); 58 b.push_back(i); 59 } 60 cout << "向量a:" << endl; 61 for (vector<int>::iterator iter = a.begin(); iter != a.end(); ++iter) 62 cout << *iter << ' '; 63 cout << endl; 64 cout << "使用for_each" << endl; 65 for_each(a.begin(), a.end(), square);//调用square函数 66 for (vector<int>::iterator iter = a.begin(); iter != a.end(); ++iter) 67 cout << *iter << ' '; 68 cout << endl; 69 70 cout << "向量b:" << endl; 71 for (vector<int>::iterator iter = b.begin(); iter != b.end(); ++iter) 72 cout << *iter << ' '; 73 cout << endl; 74 75 cout << "使用transform算法,不能传引用" << endl; 76 transform(b.begin(), b.end(), b.begin(), square2); 77 78 for (vector<int>::iterator iter = b.begin(); iter != b.end(); ++iter) 79 cout << *iter << ' '; 80 cout << endl; 81 82 83 return 0; 84 }