C++第四次作业-1000以内偶数和和乘法口诀表

#include <iostream>

using namespace std;

int main()
{
int a=2,sum=0;
while(a<=1000)
{
sum+=a;
a=a+2;
}
cout<<"sum="<<sum<<endl;
return 0;

}

#include <iostream>

using namespace std;

int main()
{
int a,sum=0;
for(a=1;a<=1000;a++)
if(a%2==0)
sum+=a;
cout<<sum;
return 0;

}

#include <iostream>

using namespace std;

int main()
{
int a=0,sum=0;
do
{
sum+=a;
a=a+2;

}
while(a<=1000);
cout<<sum;
return 0;

}

#include <iostream>

using namespace std;

int main()
{
int a,b,mult;
for(a=1;a<=9;a++)
{
for(b=1;b<=a;b++)
{
mult=a*b;

cout<<a<<"×"<<b<<"="<<mult<<" ";
}
cout<<endl;
}
return 0;

}

</pre><pre class="cpp" name="code">