Question 1

Please input an integer number. (output)

3 (or 4) ⏎ (input)

3 (or 4) is an odd (or even) number . (output)

#include<stdio.h>

int main (void) {
    int input;
    int i;
    
    printf("Please input an integer.\n");
    scanf("%d", &input);
    
    if (input % 2 == 0) {
        printf("%d is an even number\n", input);
    } else {
        printf("%d is an odd number\n", input);
    }

    return 0;
}

Download even_odd.c

Question 2

Please input your height (cm) and weight (kg). (output)

172.3 ⏎ (input)

65.0 ⏎ (input)

Your BMI is 21.890. (output)

The standard BMI is assumed to be 24.0. (output)

I’m afraid you are overweight (or underweight). (output)

#include<stdio.h>

int main (void) {
    double height, weight, BMI;
    double height_meter;
    
    printf("Please input your height (cm) and weight (kg).\n");
    scanf("%lf", &height);
    scanf("%lf", &weight);
    
    height_meter = height / 100.0;
    
    BMI = (weight) / (height_meter * height_meter);
    
    printf("Your BMI is %.2lf.\n", BMI);
    printf("The standard BMI is assumed to be 24.0.\n");
    
    if (BMI > 24.0) {
        printf("I’m afraid you are overweight.\n");
    } else {
        printf("I’m afraid you are underweight.\n");
    }
    
    return 0;
}

Download BMI.c

Question 3

Please input an integer number (> 1). (output)

7 ⏎ (input)

7 is a prime number. (output)

Please input an integer number (> 1). (output)

15 ⏎ (input)

15 is not a prime number. (output)

#include<stdio.h>

int main (void) {
    int input;
    int i;
    
    printf("Please input an integer number (> 1).\n"); 
    scanf("%d", &input);
    
    for (i=2; i<=input; i++){
        if (input % i == 0 && input != i) {
            printf("%d is not a prime number.\n", input);
            break;
        }//end if
    }//end for
    
    if (i == input+1){
        printf("%d is a prime number.\n", input);
    }//end if
    return 0;
}

Download prime.c