愚人节晚作业

1.小数显示位数

#include "stdio.h"

main()

{

  float i;

  scanf("%f",&i);

  printf("%8.4f\n",i);

  printf("%09.3f",i);

}

2.八进制 十进制 十六进制 

#include "stdio.h"
main()
{
  int i;
  scanf("%d",&i);
  printf("%o %d %x",i,i,i);
  
}

3.big middle small

#include "stdio.h"
main()
{
   int i;
   scanf("%d",&i);
     if(i>1000)
       printf("big");
       if(i<=1000&&i>=100)
       printf("middle");
       if(i<100)
       printf("small");
   
}
4.ok not ok
#include "stdio.h"
main()
{
  int x;
  scanf("%d",&x);
    if(-1<x&&x<10){
      printf("OK");}
    
      else{
      printf("NOT OK");}
}
5.用do while循环计算2+......+100
#include "stdio.h"
main()
{
   int i=2,o=0;
   do
   {
   o=o+i;
   i=i+2;
   }
   while(i<=100);
   printf("%d",o);

}
6.用while循环计算2+......+100
#include "stdio.h"
main()
{
   int i=2,o=0;
  
   while(i<=100)
   {
   o=o+i;
   i=i+2;
   }
   printf("%d",o);
}
7.用for循环计算2+4......+100
#include "stdio.h"
main()
{
   int i,o=0;
   for(i=2;i<=100;i=i+2)
     o=o+i;
     printf("%d",o);
      
    
  
}
8.输入数字输出对应月份
#include "stdio.h"
main()
{
   int i;
   scanf("%d",&i);
   switch(i)
   {
   case 1:printf("January");break;
   case 2:printf("February");break;
   case 3:printf("March");break;
   case 4:printf("April");break;
   case 5:printf("May");break;
   case 6:printf("June");break;
   case 7:printf("July");break;
   case 8:printf("August");break;
   case 9:printf("September");break;
   case 10:printf("October");break;
   case 11:printf("November");break;
   case 12:printf("December");break;
   default:printf("not valid month number");
   }
   
        
}