# include<stdio.h>
# include<stdlib.h>
# include<windows.h>

int main(void)
{
    int i,j;
    int x=0;
    int y=5;
   
    int velocity_x=1;
    int velocity_y=1;
    int left=0;
    int right=20;
    int top=0;
    int bottom=10;

    while(1)
    {
        x=x+velocity_x;
        y=y+velocity_y;
        
        system("cls");
        for(i=0;i<x;i++)
            printf("\n");
        for(j=0;j<y;j++);
            printf(" ");
        printf("O");
        printf("\n");
        Sleep(50);
        
        if((x==top)||(x==bottom))
            velocity_x=-velocity_x;
        if(y==left)||(y==right))
            velocity_y=-velocity_y;
    }

}
 编译后出错

有没有大神救下我这样的小白啊

这个已经改了，但还是不行