C语言程序设计课后作业2

*源程序：exp4_12(1).cpp*/
#include<stdio.h>
#include<stdlib.h>
void main()
{
    int r;
    int g;
    r=rand();
    printf("input a number:");
    scanf_s("%d",&g);
    if(g==r)
      printf("Right!\n");
}

/*源程序：exp4_12(2).cpp*/
#include<stdio.h>
#include<stdlib.h>
void main()
{
    int r;
    int g;
    r=rand();
    printf("input a number:");
    scanf_s("%d",&g);
    if(g==r)
      printf("Right!\n");
    else
      printf("The number is:%d,You are wrong!\n",r);
}

/*源程序：exp5_2.cpp*/
#include<stdio.h>
void main()
{ int i=1;
  int sum=0;
  while(i<=100)
  { sum=sum+i;
    i++;

  }
  printf("sum=%d\n",sum);
}
 

/*源程序：exp5_5.cpp*/
#include<stdio.h>
void main()
{ int i;
  int sum=0;
  for(i=1;i<=100;i++)
  {
       sum=sum+i*(i+1);
  }
  printf("1*2+2*3+3*4+...+100*101=%d\n",sum);
}