这为什么错???

main()
{
int tall,weight,normal,fat,thin;
printf("please input tall and weight:");
scanf("%f%f",&tall,&weight);
normal==tall-110;
if(normal-5<=weight<=normal+5)
printf("%s\n","normal");
else if(weight>normal+5)
printf("%s\n","fat");
else if(weight<normal-5)
printf("%s\n","thin");
}

#include <stdio.h>

main()
{
int tall,weight,normal,fat,thin;
printf("please input tall and weight:");
scanf("%d%d",&tall,&weight); // int要用%d
normal==tall-110;
if(normal-5<=weight && weight<=normal+5)
printf("%s\n","normal");
else if(weight>normal+5)
printf("%s\n","fat");
else if(weight<normal-5)
printf("%s\n","thin");
}

#include<stdio.h> main() { int tall,weight,norm; printf("please input tall and weight:"); scanf("%d%d",&tall,&weight); norm=tall-110; if((norm-5)<=weight&&weight<=(norm+5)) printf("normal\n"); else if(weight>norm+5) printf("fat\n"); else if(weight<norm-5) printf("thin\n"); }

这是修改后的程序，在DEV-C++编译器上可以正常运行

main() { int tall,weight,normal,fat,thin; printf("please input tall and weight:"); scanf("%d,%d",&tall,&weight); normal=tall-110; if(normal-5<=weight&&weight<=normal+5) printf("%s\n","normal"); else if(weight>normal+5) printf("%s\n","fat"); else if(weight<normal-5) printf("%s\n","thin"); }

normal-5<=weight<=normal+5

这个地方不能这样写，C语言中a<b<c只能通过a<b&&b<c方式写。

原因：

如果写成a<b<c，由于两个<号优先级相同，因此先计算a<b，得到一个结果（真为1，假为0），然后再把这个结果与c比，造成出错。

normal==tall-110;不能用双=号，而且normal-5<=weight<=normal+5也有误， normal =tall-110; normal-5<=weight&&weight<=normal+5; 好久没用c了，现在在学java，大体一样的。