Percentage Message Using switch in C

Algorithm

1. Read the percentage as an integer and reject values outside 0 to 100.
2. Compute band = percentage / 10, which gives 0 to 10.
3. Use switch on band: 10 and 9 print Outstanding, 8 prints Excellent, 7 and 6 print First Class, 5 prints Second Class, 4 prints Pass, and all other values print Fail.

C program

#include <stdio.h>

int main(void) {
    int percentage, band;

    printf("Enter percentage of marks (0-100):\n");
    if (scanf("%d", &percentage) != 1 || percentage < 0 || percentage > 100) {
        printf("Error: percentage must be from 0 to 100\n");
        return 1;
    }

    band = percentage / 10;
    switch (band) {
        case 10:
        case 9:
            printf("Outstanding\n");
            break;
        case 8:
            printf("Excellent\n");
            break;
        case 7:
        case 6:
            printf("First Class\n");
            break;
        case 5:
            printf("Second Class\n");
            break;
        case 4:
            printf("Pass\n");
            break;
        default:
            printf("Fail\n");
            break;
    }
    return 0;
}

Sample input and output

75

Enter percentage of marks (0-100):
First Class

100

Enter percentage of marks (0-100):
Outstanding

How the program works

Integer division by 10 turns each ten-mark range into a single case label, so the switch stays short. Cases 10 and 9 share one body, and 7 and 6 share another, because a missing break makes execution fall through to the next case.

Fall-through is used deliberately here. Each shared group ends with a single break so that no other band's message is printed.

Viva questions

Common mistakes

• Forgetting break, which prints several messages in a row.
• Using a percentage as a case label instead of the band, which only matches exact values.