#include
#include

int main() {

using std::cout;
    using std::endl;
    using std::string;
    const int rows = 10;
    const string::size_type cols = 5;
for  (int r = 0; r != rows; r++){
    string::size_type c = 0;
    while (c!=cols){
        if (r==3||r==6||r==7||r==8){
            if (r == 3 || r == 6)
            
                cout << " ";
                
            
            else
            {
                if ((r==7&&c==2)||(r==8&&c==1)||(r==8&&c==3))
                {
                    cout << "#";


                }
                else
                {
                    cout << " ";

                }
                
            }
            }

        
        else {
            cout << "#";
        }
        ++c;
    }

}
return 0;

}

运行出来是这
############### ########## # # # #####

可是我想要的是：
#####
#####
#####

#

到底错在哪了，我为啥只打出行。

在while的外面加一句：cout << endl;就可以了，你没有换行

#include<iostream>


int main() {
    using std::cout;
    using std::endl;
    using std::string;
    const int rows = 10;
    const string::size_type cols = 5;
    for (int r = 0; r != rows; r++) {
        string::size_type c = 0;
        while (c != cols) {
            if (r == 3 || r == 6 || r == 7 || r == 8) {
                if (r == 3 || r == 6)
                    cout << " ";
                else
                {
                    if ((r == 7 && c == 2) || (r == 8 && c == 1) || (r == 8 && c == 3))
                    {
                        cout << "#";


                    }
                    else
                    {
                        cout << " ";
                    }
                }
            }
            else {
                cout << "#";
            }
            ++c;
        }
        cout << endl;  //这里换行
    }
    return 0;
}