c - 关系运算符的链接给出了错误的输出

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有人可以向我解释吗？我做错什么了吗？
当我运行程序时，它没有显示正确的答案。

例如：当我输入体重= 50公斤，身高= 130厘米时，答案应该是


  “您的BMI是29.58。您超重2。您将有机会引起高血压，糖尿病需要控制饮食。还有健身。”


但显示的答案是


  “您的BMI是29.58。您很正常......”

#include<stdio.h>
#include<conio.h>

int main() {
  float weight, height, bmi;

  printf("\nWelcome to program");

  printf("\nPlease enter your weight(kg) :");
  scanf("%f", &weight);

  printf("\nPlease enter your height(cm) :");
  scanf("%f", &height);

  bmi=weight/((height/100)*(height/100));

  if(bmi<18.50) {
    printf("Your bmi is : %.2f",bmi);
    printf("You are Underweight.You should eat quality food and a sufficient amount of energy and exercise proper.");
  } else if(18.5<=bmi<23) {
    printf("Your bmi is : %.2f \nYou are normal.You should eat quality food and exercise proper.",bmi);
  } else if(23<=bmi<25) {
    printf("Your bmi is : %.2f \nYou are overweight1 if you have diabetes or high cholesterol,You should lose weight body mass index less than 23. ",bmi);
  } else if(25<=bmi<30) {
    printf("Your bmi is : %.2f \nYou are overweight2.You will have a chance to cause high blood pressure and diabetes need to control diet. And fitness.",bmi);
  } else if(bmi>=30) {
    printf("Your bmi is : %.2f \nYou are Obesity.Your risk of diseases that accompany obesity.you run the risk of highly pathogenic. You have to control food And serious fitness.",bmi);
  } else {
    printf(" Please try again! ");
  }

  return 0;
  getch();
}

最佳答案

在您的代码中，您尝试过的

 else if(18.5<=bmi<23)

不，这种关系运算符的链接在C语言中是不可能的。您应该写

 else if((18.5<=bmi) &&  (bmi < 23))

检查其他情况下的bmi中的[18.5, 23)值，依此类推。



编辑：

只是为了详细说明这个问题，类似

18.5<=bmi<23

是完全有效的C语法。但是，它基本上与

((18.5<=bmi) < 23 )

由于operator associativity。

因此，首先对(18.5<=bmi)求值，结果（0或1）与23对应，这当然不是您想要的。

关于c - 关系运算符的链接给出了错误的输出，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/35059133/