Mystring函数(编程练习代码)

//my string
#include "stdio.h"
#include<string.h>
#define num 15
void Mystrcpy (char stringone[], char stringtwo[],int N )
{
int i;
for(i=0;i<N;i++)
{
stringtwo=stringone;
}
}
int Mystrlen( char *a)
{
int i=0;
for(;*a!='\0'; a++)
{i++;}
return i;
}
int Mystrcmp(char *a,char *b)
{

for(;(*a!=*b)&&(*a=='\n'||*b=='\0');)
{a++;b++;}
if(*a>*b)return 1;
else if (*a==*b) return 0;
else if (*a<*b) return -1;

}
void main()
{

int c;
printf("Mystrcpy-------1\n");
printf("Mystrlen-------2\n");
printf("Mystrcmp-------3\n");
printf("please change:");
scanf("%d",&c);

if(c==1)
{
char strone[num]; char strtwo[num];
char *a;char *b;

a=strone;
b=strtwo;
printf("please enter the stringone :");
char m;
scanf("%c",&m);
gets(strone);
Mystrcpy(a,b,num);
puts(b);

}
else if(c==2)
{

char str[num];
char *a;
a=str;
printf("plase enter str:");
char m;
scanf("%c",&m);
gets(str);

printf("%d\n",Mystrlen(a));
}
else if (c==3)
{
char strone[num],strtwo[num];
char *a,*b;
a=strone;b=strtwo;
printf("plase enter strone and strtwo:");
char m;
scanf("%c",&m);
gets(strone);
gets(strtwo);
int x;
x=Mystrcmp(a,b);
if (x==1)
printf("strone>strtwo\n");
else if (x==0)
printf("strone=strtwo\n");
else if (x==-1)
printf("strone<strtwo\n");
}
}