c语言高手这为什么错了??

#include <stdio.h>
main()
{
float a,b,c,weight,nomal,height,thin,fat;
printf("please input height(cm),weight(kg):");
scanf("%f%f",&height,&weight);
a=height;
b=weight;
c=nomal;
c=(a-110);
if (c-5<=b<=c+5)
printf("%s\n","nomal");
if (b>c+5)
printf("%s\n","fat");
if (b<c-5)
printf("%s\n","thin");
}

if (c-5<=b<=c+5)
改为

if (c-5<=b&&b<=c+5)

if (c-5<=b<=c+5) 错了

应该写成if ((c-5<=b)&&(b<=c+5))

if (c-5<=b<=c+5) 改为

if (c-5=<bb<=c+5)

要看那个=与>和<的顺序

还有就是C语言中&&表示且的意思。。只能用它来表示且