CODEWITHSUNDEEP
ccodeblocks
PaoPaoMC
PaoPaoMC

Reputation: 87

Get error when user has input a string in a scanf that keep float variable

I am practicing c programming now and I made some BMI calculator. It works great but when user input string or character on the first scanf that send data to float variable 'weight' . It passed all scanf after that and showed error to me that Your BMI is 1.#J . How to solve this error? Here is my code. 

#include <stdio.h>

int main()
{
  float weight;
  float height;
  float result;
  float c_height;

  printf("Enter your weight as kilogram...\n\n> ");
  scanf("%f",&weight);
  //If user input char or string , it passed all thing and showed error.

  printf("\nEnter your height as centimetres...\n\n> ");
  scanf("%f",&height);

  c_height=(height/100)*(height/100);
  result=weight/c_height;

  if(result<18.50)
  {
    printf("\nYour BMI is %.2f\n\n",result);
    printf("You are underweight! Try to eat more frequently\n\n");
    printf("Thank you for using my program!\n\n");

}else if(result>=18.50 && result<22.90)
{
    printf("\nYour BMI is %.2f\n\n",result);
    printf("You are healthy! Keep eating healthy\n\n");
    printf("Thank you for using my program!\n\n");

}else if(result>=22.90 && result<24.90)
{
    printf("\nYour BMI is %.2f\n\n",result);
    printf("You are a little overweight! Avoid eating some fat and an oil\n\n");
    printf("Thank you for using my program!\n\n");

}else if(result>=24.90 && result<29.90)
{
    printf("\nYour BMI is %.2f\n\n",result);
    printf("You are overweight! Avoid eating fat and do exercise often\n\n");
    printf("Thank you for using my program!\n\n");

}else if(result>=29.90)
{
    printf("\nYour BMI is %.2f\n\n",result);
    printf("You are obese! Do exercise everyday and eat carefully!\n\n");
    printf("Thank you for using my program!\n\n");

}else
{
    printf("Error occured!!");
}
return 0;

}

Upvotes: 1

Views: 627

Answers (2)

lostbard
lostbard

Reputation: 5220

scanf will return the number of values read in, so should be one in your example, as you are reading in a single float value.

You could check that scanf returns that value and if it doesn't do some kind of recovery such as reading until end of line:

while(scanf("%f",&height) != 1)
{
  int c;
  while((c = getchar()) != '\n' && c != EOF)
    ;
  printf("Enter your weight as kilogram...\n\n> ");
}

Upvotes: 5

Malek Zarkouna
Malek Zarkouna

Reputation: 988

To pass to the next argument add an fflush(stdin) after the scanf :

scanf("%f",&weight);

  fflush(stdin);

and you need to controle your input like this :

if (scanf("%lf", &weight) == 1)
    printf("It's float: %f\n", weight);
else
    printf("It's NOT float ... \n");

Upvotes: 0

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