Thread: else if statement with example

I want to write c program to display status of student. if student get less then 40 marks then print " Failed". if he get mark's 40-50 then print "average. if he get marks 50- 70 then print "good" if he get mark's 70-100 then print "excellent "

I was trying to write program but I am not getting status of student. How to print different status of students ?

Code:

#include<stdio.h>
    
int main(void)
{
 int marks;
 
 printf(" exam marks : ");
 
 scanf("%d", &marks);
 
 
 if (0 < marks && marks > 40)
 {
  printf ("failed");
 }
 
 else if (40 < marks && marks > 50)
 {
       printf ("average");
 }
    
 else if (50 < marks  && marks > 70)
 {
       printf ("Good");
 }
 return 0;
   
 }

Code:

if (0 < marks && marks > 40)

is the same as:

Code:

if (marks > 0 && marks > 40)

in this case, whenever marks is equal or less than 40, this if condition will evaluate to false. It may as well be simplified to:

Code:

if (marks > 40)

In the same way:

Code:

else if (40 < marks && marks > 50)

can be simplified to:

Code:

else if (marks > 50)

and:

Code:

else if (50 < marks && marks > 70)

can be simplified to:

Code:

else if (marks > 70)

So if this is all put together, the code you have written above would work out exactly the same as this code below:

Code:

#include <stdio.h>
 
int main(void) {
    int marks;
    printf(" exam marks : ");
    scanf("%d", &marks);
 
    if (marks > 40)    {
        printf("failed");
    }
    else if (marks > 50) {
        printf("average");
    }
    else if (marks > 70) {
        printf("Good");
    }
}

Now looking at this code, it is easier to see that the bottom two else if statements will never be processed. When the top if statement is false, the conditions in the else if statements are set to be false as well. When the top if statement is true, the else if statements will be skipped.

Originally Posted by vead

No your program are wrong. I have checked it. when I enter exam marks : 42 this print "failed" and when I enter exam marks : 38 this doesn't print anything

Please read again what Jack said.

if/else if/else statements are linked together. If one of them gets executed, the others are skipped. Therefore if "marks" is larger than 50, it's also larger than 40 and only the first if would be run.

What you probably meant to do and totally got backwards is "marks < 40".

I'd try from a top down process of elimination approach. Start at the (top) highest first then work your way down and when you get to the bottom the only thing left is failing scores, so it'd read something like this

Code:

if ( condition )
Good
else if ( condition )
average
else
fail

Originally Posted by vead

if user enter any marks between 0 to 40 , then print "fail"
if user enter any marks between 50 to 70 , then print "average"
if user enter any marks between 70 to 100, then print "good"

How to write program for above conditions?

You cannot have 70 be equal to both good and average. that is called what?
then you have a big gap between 40 and 50 what happens to them peoples scores?

Code:

#include <stdio.h>
int main()
{
    
    printf("Enter score\n");
    int score = 0;
    scanf(" %d", &score);

    // applying process of elimination 

    if(score >= 70)
        printf("Good\n");
    else if (score >= 41)
        printf("OK\n");
    else
        printf("fail\n");
            
return 0;    
}

just reverse the logic

Originally Posted by vead

Have you tested your code?
When I compile your program I am getting error

why? it works on mine. it is basic C code. what is the error?

this is the results of both methods, the one I posted, then the one you're working on.

Code:

$ ./student_grades
Enter score
30
fail
Enter score again
70
HIGH SCORE

he is using scanf and nothing more or less then what I used in my code. Look at his post #1
eidt the only two things I see different is I did't add 'void' in main, and my declaring of int is between the printf and the scanf
my if, else if, else .. well that is just what should be used. not if , else if, else if

mine

Code:

#include <stdio.h>
int main()
{
     
    printf("Enter score\n");
    int score = 0;
    scanf(" %d", &score);
 
    // applying process of elimination 
 
    if(score >= 70)
        printf("Good\n");
    else if (score >= 41)
        printf("OK\n");
    else
        printf("fail\n");
             
return 0;    
}

his

Code:

#include<stdio.h>
     
int main(void)
{
 int marks;
  
 printf(" exam marks : ");
  
 scanf("%d", &marks);
  
  
 if (0 < marks && marks > 40)
 {
  printf ("failed");
 }
  
 else if (40 < marks && marks > 50)
 {
       printf ("average");
 }
     
 else if (50 < marks  && marks > 70)
 {
       printf ("Good");
 }
 return 0;
    
 }

the bold is the only two differences I see. as I do not know the differences between C90 and C99 and if it is an if statement maybe brackets even?

it is not like he cannot make the needed adjustments, that is why I asked what is the error he is getting.