C program to enter student marks and find percentage and grade

Write a C program to input marks of five subjects Physics, Chemistry, Biology, Mathematics and Computer, calculate percentage and grade according to given conditions:
If percentage >= 90% : Grade A
If percentage >= 80% : Grade B
If percentage >= 70% : Grade C
If percentage >= 60% : Grade D
If percentage >= 40% : Grade E
If percentage < 40% : Grade F

Input marks of five subjects: 95
95
97
98
90

Percentage = 95.00 
Grade A

Required knowledge

Basic C programming, Relational operators, If else

Logic to calculate percentage and grade

In primary mathematics classes you have learned about percentage. Just to give a quick recap, below is the formula to calculate percentage.

Step by step descriptive logic to find percentage and grade.

1. Input marks of five subjects in some variable say phy, chem, bio, math and comp.
2. Calculate percentage using formula per = (phy + chem + bio + math + comp) / 5.0;.
   Carefully notice I have divided sum with 5.0, instead of 5 to avoid integer division.
3. On the basis of per find grade of the student.
4. Check if(per >= 90) then, print “Grade A”.
5. If per is not more than 90, then check remaining conditions mentioned and print grade.

Program to find percentage and grade

/**
 * C program to enter marks of five subjects and find percentage and grade
 */

#include <stdio.h>

int main()
{
    int phy, chem, bio, math, comp; 
    float per; 

    /* Input marks of five subjects from user */
    printf("Enter five subjects marks: ");
    scanf("%d%d%d%d%d", &phy, &chem, &bio, &math, &comp);


    /* Calculate percentage */
    per = (phy + chem + bio + math + comp) / 5.0;

    printf("Percentage = %.2f\n", per);


    /* Find grade according to the percentage */
    if(per >= 90)
    {
        printf("Grade A");
    }
    else if(per >= 80)
    {
        printf("Grade B");
    }
    else if(per >= 70)
    {
        printf("Grade C");
    }
    else if(per >= 60)
    {
        printf("Grade D");
    }
    else if(per >= 40)
    {
        printf("Grade E");
    }
    else
    {
        printf("Grade F");
    }

    return 0;
}

Note: %.2f is used to print fractional values up to two decimal places. You can also use %f normally to print fractional values up to six decimal places.

Enter five subjects marks: 95
95
97
98
90
Percentage = 95.00
Grade A

Happy coding 😉