C Program to Find Grade from Marks

Use a C program with if-else statements to check marks and print grades, for example: if(marks >= 90) printf("Grade A"); else if(marks >= 80) printf("Grade B"); and so on.

Examples

Inputmarks = 95

OutputGrade A

Inputmarks = 75

OutputGrade C

Inputmarks = 40

OutputGrade F

How to Think About It

To find the grade from marks, first get the marks as input. Then compare the marks with fixed ranges using if and else if conditions. Assign the grade based on which range the marks fall into, for example, 90 and above is A, 80 to 89 is B, and so on.

Algorithm

1

Get the marks input from the user

2

Check if marks are greater than or equal to 90, assign grade A

3

Else if marks are greater than or equal to 80, assign grade B

4

Else if marks are greater than or equal to 70, assign grade C

5

Else if marks are greater than or equal to 60, assign grade D

6

Else assign grade F

7

Print the grade

Code

c

#include <stdio.h>

int main() {
    int marks;
    printf("Enter marks: ");
    scanf("%d", &marks);

    if (marks >= 90) {
        printf("Grade A\n");
    } else if (marks >= 80) {
        printf("Grade B\n");
    } else if (marks >= 70) {
        printf("Grade C\n");
    } else if (marks >= 60) {
        printf("Grade D\n");
    } else {
        printf("Grade F\n");
    }

    return 0;
}

Output

Enter marks: 85
Grade B

Dry Run

Let's trace the program with marks = 85 through the code

1

Input marks

User enters 85, so marks = 85

2

Check if marks >= 90

85 >= 90 is false, so skip Grade A

3

Check if marks >= 80

85 >= 80 is true, so print Grade B

4

End program

Program prints Grade B and ends

Step	Condition Checked	Result	Grade Printed
1	marks >= 90	false
2	marks >= 80	true	Grade B

Why This Works

Step 1: Input marks

The program asks the user to enter marks and stores it in a variable.

Step 2: Check conditions

It uses if-else if to compare marks with grade ranges in descending order.

Step 3: Print grade

When a condition matches, the corresponding grade is printed and the program ends.

Alternative Approaches

Using switch with ranges (requires integer division)

c

#include <stdio.h>

int main() {
    int marks, grade;
    printf("Enter marks: ");
    scanf("%d", &marks);
    grade = marks / 10;

    switch(grade) {
        case 10:
        case 9:
            printf("Grade A\n");
            break;
        case 8:
            printf("Grade B\n");
            break;
        case 7:
            printf("Grade C\n");
            break;
        case 6:
            printf("Grade D\n");
            break;
        default:
            printf("Grade F\n");
    }
    return 0;
}

This method uses integer division and switch-case for cleaner code but is less flexible for non-standard ranges.

Using ternary operator

c

#include <stdio.h>

int main() {
    int marks;
    printf("Enter marks: ");
    scanf("%d", &marks);

    char grade = (marks >= 90) ? 'A' :
                 (marks >= 80) ? 'B' :
                 (marks >= 70) ? 'C' :
                 (marks >= 60) ? 'D' : 'F';

    printf("Grade %c\n", grade);
    return 0;
}

This approach is concise but can be harder to read for beginners.

Complexity: O(1) time, O(1) space

Time Complexity

The program uses a fixed number of comparisons regardless of input size, so it runs in constant time O(1).

Space Complexity

It uses a few variables and no extra data structures, so space complexity is O(1).

Which Approach is Fastest?

All approaches run in constant time; switch-case may be slightly faster but less flexible than if-else.

Approach	Time	Space	Best For
If-else	O(1)	O(1)	Simple and clear grading logic
Switch-case	O(1)	O(1)	Cleaner code with fixed ranges
Ternary operator	O(1)	O(1)	Concise code, less readable for beginners