C - Scanf not getting input [duplicate]

Question

I'm pretty new to C and I have encountered a problem. In my code, I want to get the age, gpa, and letter grade of the user. However, when I run the code, it only gets the inputs for the age and gpa, ignoring the letter grade. It only asks for 2 inputs all in all instead of 3. But if I were to individually check for inputs instead of simultaneously doing so, it functions correctly. Why is this happening?

Check my code below:

int main(void) {

  int age;
  double gpa;
  char grade;

  // int
  printf("Enter your age: ");
  scanf("%d", &age);

  // double
  printf("Enter your gpa: ");
  scanf("%lf", &gpa);

  // char
  printf("Enter your letter grade: ");
  scanf("%c", &grade);

  // prints
  printf("You are %d years old", age);
  printf("\nYour gpa is %f", gpa);
  printf("\nYour grade is %c", grade);

  return 0;
}

OUTPUT:

Enter your age: 12
Enter your gpa: 4.0
Enter your letter grade: You are 12 years old
Your gpa is 4.000000
Your grade is

You have to upvote answer if it's helpful

Faheem azaz Bhanej
– Faheem azaz Bhanej

2022-02-10 08:32:28 +00:00
Commented Feb 10, 2022 at 8:32 — Faheem azaz Bhanej
– Faheem azaz Bhanej, Commented Feb 10, 2022 at 8:32

Faheem azaz Bhanej · Accepted Answer · 2021-11-12 11:08:23Z

-1

Put scanf(" %c", &grade) instead of scanf("%c", &grade) because you need a whitespace before the %c to skip the newline that was not read when scanf stopped at the end of the number

#include <stdio.h>

int main(void) {

  int age;
  double gpa;
  char grade;

  printf("Enter your age: ");
  scanf("%d", &age);

  printf("Enter your gpa: ");
  scanf("%lf", &gpa);

  printf("Enter your letter grade: ");
  scanf(" %c", &grade);

  printf("You are %d years old", age);
  printf("\nYour gpa is %f", gpa);
  printf("\nYour grade is %c", grade);

  return 0;
}

edited Nov 12, 2021 at 11:08

answered Nov 9, 2021 at 4:58

Faheem azaz Bhanej

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Comments

Peaky_001 · Accepted Answer · 2021-11-09 12:07:34Z

-1

   int main(void) {

  int age;
  double gpa;
  char grade;

  // int
  printf("Enter your age: ");
  scanf("%d", &age);

  // double
  printf("Enter your gpa: ");
  scanf("%lf", &gpa);
Getchar();

  // char
  printf("Enter your letter grade: ");
  scanf("%c", &grade);

  // prints
  printf("You are %d years old", age);
  printf("\nYour gpa is %f", gpa);
  printf("\nYour grade is %c", grade);

  return 0;
    }

Your grade scanf statment is reading a newline character from previous statement. So , add a getchar() before grade statement which reads the newline character

edited Nov 9, 2021 at 12:07

answered Nov 9, 2021 at 4:51

Peaky_001

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5 Comments

Lucky Over a year ago

I get it now. Thank you very much. One more thing, when do I use getchar() exactly? Is it always necessary to put it when I use multiple scanfs, or is it used in special situations?

Uduru Over a year ago

@Lucky The scanf() consumes inputs until where you specify, and remember that a newline character \n, a space ' ' are all characters. use getchar() when you need to get rid of un needed characters.

Faheem azaz Bhanej Over a year ago

I think space before %c is better option it can not consume more memory

Peaky_001 Over a year ago

Getchar reads a single character from the standard input stream stdin.for example if you type 1, a 5 and then press the ENTER key. So there are now three characters in the input buffer. scanf("%d") reads the 1 and the 5.

Lucky Over a year ago

Thank you for your insights, guys! It's really helpful. I really appreciate it. I think I need to read more regarding this matter to cure my ignorance.

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