学习C++笔记174

函数必须声明才能使用：

#include

#include

using namespace std;

//float area(float a,float b);

int main()

{

    float length,width;

    length=10.0;

    width=5.0;

    float areas=area(length,width);

    cout << areas <<endl;

    return 0;

}

float area(float a,float b){

    return a*b;

}

报错：

main.cpp: In function ‘int main()’:

main.cpp:11:14: error: ‘area’ was not declared in this scope; did you mean ‘areas’?

   11 |  float areas=area(length,width);

      |              ^~~~

      |              areas