用C语言编写程序 会的看下吧 急用！！！

C：
#include
void main()
{int x,y;
printf("enter x:");
scanf("%d",&x);
if(x>-5&&x<0)
{y=x;
printf("x=%d,y=x=%d",x,y);
}
else if(x==0)
{y=x-1;
printf("x=%d,y=x-1=%d",x,y);
}
else if(0{y=x+1;
printf("x=%d,y=x+1=%d",x,y);
}
else
{printf("不符合要求");
}
}

不嵌套的if语句：
#include
void main()
{int x,y;
printf("enter x:");
scanf("%d",&x);
if(x>-5&&x<0)
{y=x;
printf("x=%d,y=x=%d",x,y);
}
if(x==0)
{y=x-1;
printf("x=%d,y=x-1=%d",x,y);
}
if(0{y=x+1;
printf("x=%d,y=x+1=%d",x,y);
}
else
{printf("不符合要求");
}
}

嵌套的if语句：
#include
void main()
{int x,y;
printf("enter x:");
scanf("%d",&x);
if(x>-5&&x<10&&x!=0)
{
if(x>-5&&x<0)
{y=x;
printf("x=%d,y=x=%d",x,y);}
else
{y=x+1;
printf("x=%d,y=x+1=%d",x,y);
}
}
else
{if(x==0)
{y=x-1;
printf("x=%d,y=x-1=%d",x,y);
}
else
printf("不符合要求");
}
}

if—else语句：
#include
void main()
{int x,y;
printf("enter x:");
scanf("%d",&x);
if(x>-5&&x<0)
{y=x;
printf("x=%d,y=x=%d",x,y);
}
if(x==0)
{y=x-1;
printf("x=%d,y=x-1=%d",x,y);
}
if(0{y=x+1;
printf("x=%d,y=x+1=%d",x,y);
}
else
{printf("不符合要求");
}
}

switch语句:
#include
void main()
{int x,y;
printf("enter x:");
scanf("%d",&x);
switch(x)
{
case -4:
case -3:
case -2:
case -1:y=x;printf("x=%d,y=x=%d",x,y);break;
case 0:y=x-1;printf("x=%d,y=x-1=%d",x,y);break;
case 1:
case 2:
case 3:
case 4:
case 5:
case 6:
case 7:
case 8:
case 9:y=x+1;printf("x=%d,y=x+1=%d",x,y);break;
default:printf("不符合要求");
}
}

#include"stdio.h"
int x,y,i;
void main(){
printf("请输入x");
scanf("%d",&x);
if(x>-5&&x<0)
i=0;
else if(x==0)
i=1;
else if(0i=2;
else
i=3;
switch(i){
case 0:{
y=x;
printf("x=%d",x);
printf(",y=%d",y);
break;}
case 1:{
y=x-1;
printf("x=%d",x);
printf(",y=x-1=%d",y);
break;}
case 2:{
y=x+1;
printf("x=%d",x);
printf(",y=x+1=%d",y);
break;}
case 3:{
printf("不符合要求");}
}
}