最简单的main函数：
int main()
{
return 0;
}C++包含两种注释，注释界定符/**/通常用于多行注释，而双斜杠//通常用于单行或半行注释。
#include <iostream>
/*
* Simple main function:
* Read two numbers and write their sum
*/
int main()
{
int sum = 0, val = 1;
// keep executing the while as long as val is less than or equal to 10
while (val <= 10)
{
sum += val; // assigns sum + val to sum
++val; // add 1 to val
}
std::cout << "Sum of 1 to 10 inclusive is "<< sum << std::endl;
return 0;
}