float a[]={63.2,-45.6,70.1,3.6,14.5};
main()
	{
	  int i,j;
	  float c;
	  printf("\n day nguoc lai \n");
	 for (i=4;i>-1;i--)
	 printf("%.1f\t",a[i]);
	 getch();
	 }

float a[]={63.2,-45.6,70.1,3.6,14.5};
main()
	{
	  int i=4;
	  printf("\n day nguoc lai \n");
	 while(i-->0)
	       printf("%.1f\t",a[i]);
	 getch();
	 }

float a[]={63.2,-45.6,70.1,3.6,14.5};
main()
	{
	  int i=4;
	  printf("\n day nguoc lai \n");
	 while(--i>0)
	       printf("%.1f\t",a[i]);
	 getch();
	 }

int i=0;
printf("%d %d",i++,i++);
i=0;
printf("%d %d",++i,i++);
getch();

0 0
1 0

1 0
2 0

#include<stdio.h>
float x[]={4,6,8,3.5},
	  y[]={2.6,3.2,4,7};
main()
	{
		float s=0;
		int i=0;
		while (1)  /* ? */
			{
				s+=x[i]*y[i];  				
                                                    if (++i >=4)
					goto ketthuc;
			}
		ketthuc:
		printf("\n Vecto x[]={4,6,8,3.5}");
		printf("\n Vecto y[]={2.6,3.2,4,7}");
		printf("\nTich vo huong cua 2 vecto X va Y = %8.2f ",s);
		getch();
	}

float a[3][4]={{15,46,3.5,6.3},
			   {341,0,-25,35},
			   {1,+13,46,+31}};
main()
  {
    int i,j,cotmax[3],cotmin[3];
    float max[3],min[3];
    for(i=0;i<3;++i)
      {
			max[i]=min[i]=a[i][0];
			cotmax[i]=cotmin[i]=0;
			for(j=1;j<4;++j)
			 {
				 if(max[i]<a[i][j])
					{
						max[i]=a[i][j];
						cotmax[i]=j;
					}
				 if(min[i]>a[i][j])
					{
						min[i]=a[i][j];
						cotmin[i]=j;
					}
			 }
       }
	for(i=0;i-3;i++)
	printf("\nHang %d max = a[%d,%d]= %5.2f  min =a[%d,%d]=%5.2f"\
	  ,i+1,i+1,cotmax[i]+1,max[i],i+1,cotmin[i]+1,min[i]);	getch();
  }