#include <stdio.h>
int strcmp(char *p1,char *p2)
{
int i,h,j,k;
for (i=0;p1[i]!='\0' || p2[i]!='\0';i++)
{
	if (*(p1+i)!=*(p2+i))
	{
		h=(int)*(p1+i);
		j=(int)*(p2+i);
		k=h-j;
		return k;
	}
}
printf("The same word\n");
return 0;
}
 
int main()
{
	char s1[100],s2[100];
	int result;
	printf("Please input the first word:\n");
	gets(s1);
    printf("Please input the second word:\n");
	gets(s2);
	result=strcmp(s1,s2);
	printf("%d",result);
	return 0;
}

#include <stdio.h>
#include <string.h>
void copyx(char *x,char *y,int i);
int main()
{
	char str1[100],str2[100];         //[]里的数字足够大即可
	int l,i;
	printf("Please input the first word:\n");
	scanf("%s",str1);
	printf("Please input the second word:\n");
	scanf("%s",str2);
	l=strlen(str1);
	printf("Where do you want to insert the second word (From 1 to %d)\n",l);
	scanf("%d",&i);
	if (i<=0 || i>l)
	{
		printf("Wrong Number!\n");
		return 0;
	}
	copyx(str1,str2,i);
	printf("%s",str1);
	return 0;
}
 
void copyx(char *x,char *y,int n)
{
    int j;
    for (j=0;y[j]!='\0';j++)
	{
	  *(x+n+j)=*(y+j);
        }
    *(x+n+j)='\0';
}

#include <stdio.h>
void findnum (int *n);
int main()
{
	int i,a[20];
	printf("Please input 20 numbers:\n");
	for (i=0;i<=19;i++)
	{
		scanf("%d",&a[i]);
	}
	findnum(a);
	return 0;
}
 
void findnum (int *a)
{
	int biggest=a[0],smallest=a[0],j;
	for (j=0;j<=19;j++)
	{
		if (*(a+j)>biggest) biggest=*(a+j);
		if (*(a+j)<smallest) smallest=*(a+j);
	}
	printf("The Biggest Number is=%d\n",biggest);
	printf("The Smallest Number is=%d\n",smallest);
}

#include <stdio.h>
int leijia(int num)
{
	int f;
	if (num==1) f=1;
	else f=leijia(num-1)+num;
	return (f);
}
int main()
{
	int num,result;
	printf("Please input a number:\n");
	scanf("%d",&num);
	result=leijia(num);
	printf("The result is:\n");
	printf("%d\n",result);
	return 0;
}

#include <stdio.h>
int main()
{
	int a,m;
	for (a=2;a<=100;a++)
	{
		m=2;
		while (m<a)
		{
			if (a%m==0) break;
			m++;
		}
		if (m==a) printf("%d\n",a);
	}
	return 0;
}

#include <stdio.h>
#include <math.h>
void ss (int m)
{
	int a;
	double n;
	n=sqrt(m);
	for (a=2;a<=n;a++)
	{
		if (m%a==0) break;
	}
	if (a<=n) printf("It's not a prime.\n");
	else printf("It's a prime.\n");
}
int main()
{
    int m;
	printf("Please input a number:\n");
	scanf("%d",&m);
	ss(m);
	return 0;
}

#include<stdio.h>
#define N 10
void paixu(int a[])
{
    int i,j,t;
    for(i=0;i<N-1;i++)
      {
	   for(j=0;j<N-1-i;j++)
        {
		 if(a[j]<a[j+1])
          {
           t=a[j+1];
           a[j+1]=a[j];
           a[j]=t;
          }
		}
	  }
    printf("The right order is:\n"); 
	for(i=0;i<=N-1;i++)
     {
	   printf("%d\n",a[i]);
	  }
}
 
int main()
{
	int i,a[N];
	printf("please input 10 numbers:\n");
    for(i=0;i<=N-1;i++)
	 {
      scanf("%d",&a[i]);
     }
    paixu(a);
	return 0;
}

#include <stdio.h>
#include <string.h>
int main()
{
  int i,x,t;
  char a[10];     //10可以换成足够大的数
  printf("Please input a text.\n")
  scanf("%s",a);
  i=strlen(a)-1;
  for (x=0;x<=1;x++)
   {
	 t=a[x];
	 a[x]=a[i];
	 a[i]=t;
	 i--;
	}
  puts(a);
  return 0;
}