我发现函子可以用来模拟在函数中定义函数,如下所示
using namespace std;
int main(int argc, char* argv[])
{
struct MYINC {
int operator()(int a) { return a+1; }
} myinc;
vector<int> vec;
for (int i = 0; i < 10; i++) vec.push_back(myinc(i));
return 0;
}
但是如果我将它传递给外部函数,例如标准::变换就像下面的例子一样,我有一个编译错误:error: no matching function for call to ‘transform(std::vector<int>::iterator, std::vector<int>::iterator, std::vector<int>::iterator, main(int, char**)::MYINC&)’
using namespace std;
int main(int argc, char* argv[])
{
struct MYINC{
int operator()(int a) { return a+1; }
} myinc;
vector<int> vec;
for (int i = 0; i < 10; i++) vec.push_back(i);
transform(vec.begin(), vec.end(), vec.begin(), myinc);
return 0;
}
所以我把定义放在外面main功能现在一切正常。
using namespace std;
struct MYINC{
int operator()(int a) { return a+1; }
} myinc;
int main(int argc, char* argv[])
{
vector<int> vec;
for (int i = 0; i < 10; i++) vec.push_back(i);
transform(vec.begin(), vec.end(), vec.begin(), myinc);
return 0;
}