这次我真的不清楚问题出在哪儿了。

//Listing 5.7 - demonstrates use
//of default parameter values
#include <iostream>

int AreaCube(int length,int width = 25,int height = 1);

int main()
{
int length = 100;
int width = 50;
int height = 2;
int area;

area = AreaCube(length,width,height);
std::cout << "First area equals:" << area << "\n";

area = AreaCube(length,width);
std::cout << "Second time area equals:" << area << "\n";

area = AreaCube(length);
std::cout << "Third time area equals:" << area << "\n";
char response;
std::cin >> response;
return 0;
}

AreaCube(int length,int width,int height)
{

return (length*width*height);
}

编译提示： ISO C++ forbids declaration of `AreaCube' with no type ，而且提示出错的地方是倒数第四行的{

int AreaCube(int length,int width,int height)
{

return (length*width*height);
}

加个int在前面

顶2、3楼

此种错误实在是……
我也犯过，连自己都气愤，当发现的时候。